Term 1 β Life and Living
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1. The Scientific Method & Variables
ExperimentCan provide proof of a theory.
Scientific investigationUsed to determine a relationship between variables and confirm/reject a hypothesis.
Independent variableThe variable the scientist deliberately changes. (I control = the scIentist controls)
Dependent variableThe variable observed/measured β changes in response to the independent variable.
Controlled variableQuantities kept constant so the test is fair.
Investigative questionIncludes BOTH variables, asks about their relationship, ends with '?', cannot be answered yes/no.
HypothesisExpected outcome β includes both variables and their relationship ('If β¦, then β¦').
Fair testOnly ONE variable is changed at a time.
Reliable testExperiment is repeated several times (a few trials).
ConclusionAnswers the investigative question; contains both variables; confirms/rejects the hypothesis.
β Common Mistake: Changing many things at once gives more information
β Correct ideaIf you change MORE than one variable you cannot tell which change caused the observed result. Only ONE variable (the independent) may be changed at a time.
π Graph ruleIndependent variable β x-axis (horizontal). Dependent variable β y-axis (vertical).
Definitions Drill: Scientific Method
1. The variable the scientist deliberately changes is called the ____________ variable.
2. The variable that is measured or observed (it responds to changes) is called the ____________ variable.
3. Quantities the scientist deliberately keeps the same are called ____________.
4. A prediction of the expected outcome written as 'If β¦, then β¦' is called a ____________.
5. A test in which only ONE variable is changed at a time is called a ____________.
6. Repeating an experiment several times makes the results more ____________.
7. The part of a report that answers the investigative question and confirms/rejects the hypothesis is the ____________.
8. A test that can provide proof of a theory is called an ____________.
9. The investigative question must include both ____________ and ask about their relationship.
10. On a graph, the independent variable goes on the ____________-axis.
Practice Questions: Scientific Method
1. In an investigation: 'How does the amount of fertiliser affect plant height?' β the INDEPENDENT variable is:
2. In the same investigation the DEPENDENT variable is:
3. Which investigative question is CORRECTLY written?
4. Why must an experiment be repeated several times?
5. 'Temperature of the water' is an example of a CONTROLLED variable when testing how ____________ affects dissolving rate.
6. The dependent variable is placed on which axis of a graph?
7. 'If sunlight increases, then the rate of photosynthesis will increase.' This is a:
8. Why must an investigative question NOT be answerable with yes/no?
9. A student changes the colour of light given to plants. Temperature, water, and soil are kept the same. The colour of light is the:
10. Why must everything EXCEPT the independent variable be kept the same?
11. What happens if the hypothesis turns out to be FALSE after testing?
12. In which format must a hypothesis be written?
2. Cells β Plant & Animal
CellThe smallest unit of all living organisms.
OrganelleA specialised structure within a cell performing a specific function.
NucleusContains DNA β determines inherited characteristics.
Cell membraneSurrounds cytoplasm; selectively controls what enters/exits.
CytoplasmJelly-like medium for all chemical reactions in the cell.
MitochondriaSite of cellular respiration β releases energy from glucose.
ChloroplastContains chlorophyll for photosynthesis. Plants ONLY.
Cell wallSurrounds cell membrane in plant cells β support, protection, regular shape.
VacuoleFluid-filled sac storing water, sugar, salts. Large & permanent in plants; small/absent in animals.
ChlorophyllThe green pigment in chloroplasts.
TissueGroup of cells with same structure & function (e.g. muscle tissue).
OrganComplex structure with a specific job (e.g. heart, leaf).
SystemGroup of organs working together (e.g. digestive system).
β Common Mistake: Animal cells have no vacuoles at all
β Correct ideaAnimal cells CAN have small, temporary vacuoles. To identify a PLANT cell look for THREE things: cell wall, large vacuole, AND chloroplasts.
π Levels of organisation (smallest β largest)Cell β Tissue β Organ β System β Organism
Definitions Drill: Cell Structures
1. The smallest unit of all living organisms is called a ____________.
2. A specialised structure within a cell that performs a specific function is an ____________.
3. The organelle containing DNA that determines inherited characteristics is the ____________.
4. The structure surrounding the cytoplasm that controls what passes in and out is the ____________.
5. The jelly-like substance providing the medium for chemical reactions in the cell is called ____________.
6. The organelle where cellular respiration releases energy from glucose is the ____________.
7. The organelle containing chlorophyll for photosynthesis is the ____________.
8. The rigid structure surrounding the cell membrane in plant cells is the ____________.
9. A fluid-filled sac storing water, sugar, and salts is a ____________.
10. The green pigment found in chloroplasts is called ____________.
11. A group of cells with the same structure performing the same function is called a ____________.
12. A complex structure made of different tissues with a specific job is called an ____________.
13. A group of organs working together is called a ____________.
14. Something too small to be seen with the naked eye is described as ____________.
15. An organism consisting of only one cell is called ____________.
16. An organism consisting of many cells is called ____________.
Practice Questions: Cells & Organisation
1. Which THREE structures identify a plant cell?
2. Where does cellular respiration take place?
3. Correct order from smallest to largest:
4. A chicken egg is unusual because it...
5. Which organelle controls what substances enter and leave the cell?
6. Why do animal cells NOT have chloroplasts?
7. Which is TRUE about vacuoles?
8. Muscle tissue is an example of:
9. Which is correctly matched (organelle β function)?
10. Which structure is responsible for the regular (fixed) shape of a plant cell?
11. Cells performing different jobs (muscle cells, nerve cells, red blood cells) exist because:
12. The liver belongs to more than one system. Which two?
13. The green pigment in chloroplasts is:
14. Why does a plant cell need a cell wall but an animal cell generally does not?
15. Which tissue in plants is similar to epithelium in animals?
Short Answer: Cells
1. Explain why animal cells need MORE mitochondria than plant cells.
Animal cells are more active (movement, contraction) and cannot make their own food via photosynthesis. They must release more energy through cellular respiration, which requires more mitochondria.
2. Give TWO structures present in BOTH plant and animal cells.
Any two of: nucleus, cytoplasm, cell membrane, mitochondria.
3. Explain why animal cells do not need cell walls as much as plant cells.
Plant cells need a rigid cell wall to maintain shape and support the plant (which cannot move). Animal cells have other support structures (e.g. a skeleton) and need to be flexible, so a rigid cell wall would restrict movement.
4. Tabulate TWO differences between plant and animal cells.
Plant cell has: cell wall, chloroplasts, large permanent vacuole. Animal cell has: no cell wall, no chloroplasts, small/temporary or no vacuoles.
3. Reproductive System
PubertyStage when sexual organs mature for reproduction, triggered by pituitary gland hormones.
TestosteroneSex hormone released by the testes.
OestrogenSex hormone released by the ovaries.
Secondary sexual characteristicsChanges during puberty: menstruation, breast development, pubic/facial hair, deepening voice.
OvulationRelease of a ripe egg from an ovary (~once a month).
MenstruationBreakdown & release (via vagina) of thickened uterus lining when fertilisation does NOT occur. ~28-day cycle.
FertilisationFusion of sperm and egg β zygote.
ImplantationFertilised egg embeds in uterus blood layer.
PlacentaAttaches embryo/foetus to uterus wall; feeds it; removes waste.
GestationPeriod of human pregnancy β ~40 weeks.
ZygoteCell formed immediately after fertilisation.
ContraceptivesDevices/substances (e.g. condoms) preventing pregnancy; condoms also protect against HIV/STDs.
β Common Mistake: An embryo and a foetus are the same thing
β Correct ideaAn embryo is the EARLY stage of development. A foetus is the LATER stage once major organs and body structures are recognisable.
Definitions Drill: Reproductive System
1. The stage in the life cycle when sexual organs mature for reproduction is called ____________.
2. The sex hormone released by the testes is called ____________.
3. The sex hormone released by the ovaries is called ____________.
4. The release of a ripe egg from an ovary is called ____________.
5. The breakdown and release of the thickened uterus lining (when fertilisation does not occur) is called ____________.
6. The fusion of a sperm cell and an egg cell, producing a zygote, is called ____________.
7. When the fertilised egg embeds in the thickened blood layer of the uterus, this is called ____________.
8. The structure attaching the embryo/foetus to the uterus wall, which feeds it and removes waste, is the ____________.
9. The period of pregnancy in humans (about 40 weeks) is called ____________.
10. The cell formed immediately after fertilisation is called a ____________.
Practice Questions: Reproductive System
1. What triggers puberty?
2. The fertilised egg is called a:
3. Approximate length of human gestation:
4. Which organ is part of the MALE reproductive system?
5. Which organ is part of the FEMALE reproductive system?
6. Which is NOT a secondary sexual characteristic?
7. If fertilisation does NOT take place after ovulation:
8. A function of the placenta is:
9. Condoms help by:
10. Heavy alcohol use during pregnancy risks:
11. Correct order of events:
12. What distinguishes an embryo from a foetus?
4. Digestive System
IngestionIntake of food by biting, chewing, and swallowing.
DigestionMechanical AND chemical breakdown of insoluble food into soluble nutrients.
AbsorptionSoluble nutrients pass into the bloodstream (mainly in the small intestine).
EgestionRemoval of undigested waste through the anus.
Mechanical digestionPhysical breaking, crushing, mashing of food (teeth, stomach churning).
Chemical digestionFood mixed with digestive enzymes and hydrochloric acid.
PeristalsisRhythmic muscle contractions pushing food along the digestive canal.
BileProduced by the LIVER; helps with digestion of fats.
MalnutritionA condition from a lack of nutrients.
Anorexia nervosaEating disorder: starving oneself for fear of gaining weight.
Balanced dietHealthy eating plan containing all five food groups daily.
β Common Mistake: Digestion only means chewing food
β Correct ideaChewing is only MECHANICAL digestion. Digestion = mechanical (physical breakdown) AND chemical (enzymes + acid breaking molecules apart) processes working together.
Definitions Drill: Digestive System
1. The intake of food by biting, chewing and swallowing is called ____________.
2. The mechanical and chemical breakdown of insoluble food into soluble nutrients is called ____________.
3. When soluble nutrients pass from the small intestine into the bloodstream, this is called ____________.
4. The removal of undigested waste through the anus is called ____________.
5. Rhythmic muscle contractions pushing food along the gut are called ____________.
6. The substance produced by the liver that helps digest fats is called ____________.
7. A condition resulting from a lack of nutrients is called ____________.
8. An eating disorder causing people to starve themselves for fear of gaining weight is called ____________.
9. A healthy eating plan containing all five food groups daily is called a ____________.
10. The physical breaking, crushing and mashing of food is called ____________ digestion.
11. The mixing of food with digestive enzymes and hydrochloric acid is called ____________ digestion.
Practice Questions: Digestive System
1. Which organ produces bile?
2. Absorption of nutrients mainly happens in the:
3. Rhythmic muscle contractions pushing food along the gut are called:
4. An eating disorder causing people to starve themselves in fear of gaining weight:
5. Correct order of the alimentary canal:
6. Example of MECHANICAL digestion:
7. Example of CHEMICAL digestion:
8. Open sores on the inside lining of the intestines are called:
9. Carbohydrates are mainly found in:
10. Proteins are mainly found in:
11. Long-term missing of a food group can lead to:
12. The liver belongs to BOTH the digestive AND which other system?
5. Circulatory & Respiratory Systems
BreathingInhalation (in) and exhalation (out) of air.
Gaseous exchangeDiffusion of Oβ and COβ between alveoli and capillaries.
DiffusionMovement of gas molecules from high to low concentration.
CirculationTransport of blood around the body by the heart.
Cellular respirationOβ combines with glucose in mitochondria to release energy. COβ is a by-product.
ArteriesCarry oxygenated blood AWAY from the heart under high pressure (except pulmonary arteries). Thick walls.
VeinsCarry deoxygenated blood TOWARDS the heart (except pulmonary veins). Thinner walls, valves.
CapillariesTiny vessels where gaseous exchange with body cells occurs.
β Common Mistake: All arteries carry oxygenated blood and all veins carry deoxygenated blood
β Correct ideaEXCEPTION: Pulmonary ARTERIES carry deoxygenated blood (heartβlungs). Pulmonary VEINS carry oxygenated blood (lungsβheart). Everywhere else the general rule applies.
π PathwayLungs (gas exchange) β oxygenated blood β left side of heart β arteries β capillaries near cells β gaseous exchange β cellular respiration (mitochondria) β COβ β veins β right side of heart β lungs β exhale COβ.
Definitions Drill: Circulatory & Respiratory
1. The process of inhalation and exhalation of air is called ____________.
2. Movement of gas molecules from high to low concentration is called ____________.
3. The exchange of Oβ and COβ between alveoli and capillaries is called ____________.
4. Blood vessels carrying blood AWAY from the heart under high pressure are called ____________.
5. Blood vessels carrying blood TOWARDS the heart are called ____________.
6. Tiny blood vessels where gaseous exchange with body cells occurs are called ____________.
7. The process in mitochondria where Oβ combines with glucose to release energy is called cellular ____________.
8. The transport of blood around the body by the heart is called ____________.
Practice Questions: Circulatory & Respiratory
1. Arteries have thicker walls than veins because:
2. Which vessel carries DEOXYGENATED blood from heart to lungs?
3. Movement of oxygen from blood into muscle cells is called:
4. Which process inside muscle cells requires oxygen to release energy?
5. The pulmonary VEIN carries:
6. Structure responsible for pumping blood throughout the body:
7. Blood leaving an active muscle (after Oβ has diffused into cells) is:
8. A person with chronic bronchitis would likely show:
9. Correct pathway of oxygen from air to body cell:
10. Veins contain valves. Their purpose:
11. The ALVEOLI are found in the:
12. Which correctly states the EXCEPTION to the artery/vein rule?
6. Term 1 Mixed Review
A comprehensive mixed set covering everything from Term 1 β great practice before a test!
Term 1 Mixed Review
1. A scientist measures 'plant height' β this is the:
2. The 'powerhouse' of the cell, releasing energy, is the:
3. Sperm cells are produced in the:
4. The enzyme-rich liquid produced in the mouth is:
5. The heart pumps deoxygenated blood to the lungs through the:
6. 'If I increase water given to seedlings, they will grow taller.' This is a:
7. A large, central fluid-filled space in a plant cell viewed under a microscope is most likely the:
8. The release of an egg from the ovary monthly is called:
9. Which system health issue pair is CORRECT?
10. Which structure is shared by BOTH plant and animal cells?
11. During pregnancy, nutrients pass between mother and foetus via the:
12. Mechanical and chemical digestion both happen mainly in the:
13. The independent variable goes on which axis?
14. Absorption of water takes place mainly in the:
15. Which correctly describes how a conclusion should be written?
π Exam Paper Questions β Life & Living (from past papers)
π How to use this sectionThese questions come directly from the Grade 9 FS Revision Booklets (Papers A, B & C). Try each one before revealing the answer.
Multiple Choice β Term 1 Exam Style
1. A group of similar cells performing the same function is called β¦
2. Which of the following forms part of the musculoskeletal system?
3. Digestion begins in the β¦
4. Arteries, veins and capillaries are the ___ in the circulatory system.
5. The tiny female sex cell that unites with a sperm to form a zygote is the:
6. Which system is deafness, blindness and short-sightedness associated with?
7. The part of a plant cell needed to produce glucose and oxygen is the β¦
8. The ovaries and uterus form part of the β¦
9. The correct order for the stages of reproduction is:
10. Plant cells have a fixed shape because they have β¦
11. The sequence in which food moves along the alimentary canal is β¦
12. What is the main function of the heart?
Fill in the Blank β Term 1 Exam Style
1. The small structures found inside a cell that each perform a specific function are called ____________.
2. Tough, inelastic tissue which attaches muscles to bone is called a ____________.
3. The process when an egg cell is released from the ovary is called ____________.
4. The inflow and outflow of air in the lungs is called ____________.
5. The condition where bowel movements occur less frequently and consist of hard, dry faeces is called ____________.
6. The stage in the human lifecycle when sexual organs mature for reproduction is called ____________.
7. The breaking down of food into dissolved nutrients that can be absorbed into the bloodstream is called ____________.
8. The passing out of solid undigested waste from the digestive tract via the anus is called ____________.
9. The term used to describe a person's heartbeat when they are inactive or at rest is the ____________.
10. The fusion of a sperm cell and an egg cell to produce a zygote is called ____________.
Short-Answer Questions β Term 1 Exam Style
1. Give TWO visible reasons why a cell with an irregular shape, no cell wall, and only a cell membrane is an animal cell and not a plant cell.
β’ It has an irregular/no fixed shape (no cell wall to maintain shape).
β’ It only has a cell membrane, not a cell wall.
β’ It has no chloroplasts visible.
β’ Vacuoles are small or absent. (Any TWO of these)
β’ It only has a cell membrane, not a cell wall.
β’ It has no chloroplasts visible.
β’ Vacuoles are small or absent. (Any TWO of these)
2. A student measures her heartbeat three times at rest: 21, 21 and 24 beats per 20 seconds. Calculate the average heartbeat per minute.
Average in 20 s = (21 + 21 + 24) Γ· 3 = 22 beats per 20 s
Per minute = 22 Γ 3 = 66 beats per minute
Per minute = 22 Γ 3 = 66 beats per minute
3. Is this statement TRUE or FALSE? "Some systems in the human body are more important than others." Give a reason for your answer.
FALSE. The body systems are interdependent β one system cannot function without the others. All systems work together for us to perform daily activities.
4. Explain what happens to nutrients from the moment they enter the small intestine until they reach the body cells.
Larger nutrient molecules are broken down (by enzymes and chemical digestion) to a size small enough to be absorbed into the bloodstream through the walls of the small intestine. The bloodstream then carries the nutrients to all the body cells.
5. List THREE changes that occur in the body of a male during puberty.
Any THREE of:
β’ Testicle and penis size increases
β’ Hair grows on the pubic areas, limbs, chest and face
β’ Voice becomes deeper (larynx grows)
β’ Body shape changes as skeletal muscle and bones increase in size
β’ Body odour and acne develop
β’ Testicle and penis size increases
β’ Hair grows on the pubic areas, limbs, chest and face
β’ Voice becomes deeper (larynx grows)
β’ Body shape changes as skeletal muscle and bones increase in size
β’ Body odour and acne develop
6. Name TWO body structures in the musculoskeletal system that work closely together to provide support and allow movement.
Bones and muscles.
Term 2 β Matter and Material
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1. Atoms & the Periodic Table
ElementA pure substance with only one type of atom β cannot be broken down.
AtomBuilding block of matter: protons (pβΊ) & neutrons (nβ°) in nucleus; electrons (eβ») around it.
Atomic numberNumber of protons in the nucleus (smaller number on the PT).
Mass numberNumber of protons + neutrons (larger number on the PT).
Neutrons= Mass number β Atomic number
Neutral atom ruleNumber of protons (pβΊ) = number of electrons (eβ»)
GroupVertical column on PT β elements in same group have similar chemical properties.
PeriodHorizontal row on the PT.
MetalsShiny, ductile, malleable, mostly solid (except Hg), good conductors, high melting points.
Non-metalsDull, brittle (if solid), poor conductors (except C), lower melting points.
Semi-metalsB, Si, Ge, As, Te, Sb β solid, brittle, metallic look, fair conductors.
β Common Mistake: Atomic mass and atomic number are the same thing
β Correct ideaAtomic number (smaller, top) = number of protons only. Atomic mass / mass number (larger, bottom) = protons + neutrons. Subtract to find neutrons.
Definitions Drill: Atoms & the Periodic Table
1. A pure substance consisting of only one type of atom, which cannot be broken down, is an ____________.
2. The number of protons in the nucleus of an atom is called the ____________.
3. The total number of protons AND neutrons in the nucleus is called the ____________.
4. A vertical column on the Periodic Table is called a ____________.
5. A horizontal row on the Periodic Table is called a ____________.
6. In a neutral atom, the number of electrons equals the number of ____________.
7. Elements such as B, Si, Ge, As β having properties of both metals and non-metals β are called ____________.
8. The orderly arrangement of all known elements according to atomic number is called the ____________.
9. The formula for neutrons is: mass number ____________ atomic number.
10. Elements in the same group have similar ____________ properties.
Practice Questions: Periodic Table & Atomic Structure
1. Atom with 13 protons and 14 neutrons β mass number is:
2. In a neutral atom, number of electrons = number of:
3. Elements in the same GROUP have similar:
4. Semi-metals (metalloids):
5. Oxygen (atomic number 8, mass number 16) has ____________ neutrons.
6. Which property is TYPICAL of metals?
7. Which property is TYPICAL of non-metals?
8. Mercury is unusual among metals because it is:
9. A two-letter element symbol is ALWAYS written as:
10. Which is NOT a diatomic molecule?
11. Sodium (atomic number 11, mass number 23) has ____________ neutrons.
12. Which group of elements is generally unreactive?
Calculations: Atomic Structure
1. For Β²β·ββAβ: give the number of protons, electrons (neutral atom), and neutrons.
Protons = 13; Electrons = 13 (neutral atom); Neutrons = 27 β 13 = 14.
2. For Β³ΒΉββ
P: give the number of protons, electrons, and neutrons.
Protons = 15; Electrons = 15; Neutrons = 31 β 15 = 16.
3. An unknown element has 11 protons, 11 electrons, 12 neutrons. Identify the element and write its mass number.
Atomic number = 11 β Sodium (Na). Mass number = 11 + 12 = 23. Written as Β²Β³ββNa.
2. Compounds & Naming
CompoundPure substance of two or more different elements chemically bonded in a fixed ratio.
MoleculeTwo or more atoms bonded together.
Chemical bondForce holding atoms together in a compound.
Diatomic moleculesHβ, Nβ, Oβ, Fβ, Clβ, Brβ, Iβ β two identical atoms.
| Naming pattern | Example |
|---|---|
| Metal + non-metal β metal + '-ide' | Sodium + Chlorine β Sodium chloride (NaCl) |
| mono-/di-/tri- show non-metal atom count | CO = carbon monoxide; COβ = carbon dioxide; SOβ = sulfur trioxide |
| Formula ends COβ β '-carbonate' | CaCOβ = calcium carbonate |
| Formula ends SOβ β '-sulphate' | MgSOβ = magnesium sulphate |
| Formula ends NOβ β '-nitrate' | NaNOβ = sodium nitrate |
| Formula ends OH β '-hydroxide' | KOH = potassium hydroxide |
| Formula starts NHβ β 'ammoniumβ¦' | NHβNOβ = ammonium nitrate |
β Common Mistake: The 'di' in carbon dioxide refers to two carbon atoms
β Correct ideaCOβ has ONE carbon atom and TWO oxygen atoms β 'di' refers to the TWO oxygens.
Definitions Drill: Compounds & Naming
1. A pure substance made of two or more different elements chemically bonded in a fixed ratio is a ____________.
2. Two or more atoms bonded together form a ____________.
3. The force holding atoms together in a compound is a ____________.
4. When a compound formula ends in COβ, its name ends in '-____________'.
5. When a compound formula ends in SOβ, its name ends in '-____________'.
6. When a compound formula ends in OH, its name ends in '-____________'.
7. When a compound formula ends in NOβ, its name ends in '-____________'.
8. When a compound formula starts with NHβ, its name starts with '____________'.
9. The prefix for ONE non-metal atom is '____________-' (e.g. carbon ___oxide).
10. The prefix for TWO non-metal atoms is '____________-' (e.g. carbon ___oxide).
11. The prefix for THREE non-metal atoms is '____________-' (e.g. sulfur ___oxide).
Practice Questions: Naming & Formulas
1. Name of CaCOβ:
2. Formula for magnesium oxide:
3. NHβOH is named:
4. Name of CO (one C, one O):
5. SOβ (one S, three O) is named:
6. NaNOβ is named:
7. Formula for potassium bromide:
8. (NHβ)βCOβ is named:
9. FeβOβ is named:
10. In COβ the prefix 'di' refers to:
Fill in the Blank: Write the Formulas
1. Sodium chloride:
2. Potassium hydroxide:
3. Magnesium chloride (MgΒ²βΊ + Clβ», criss-cross):
4. Calcium carbonate:
5. Lithium nitrate:
6. Carbon dioxide:
7. Magnesium sulphate:
8. Aluminium oxide (AlΒ³βΊ + OΒ²β», criss-cross):
3. Chemical Reactions & Balancing Equations
ReactantsSubstances that react β left side of the arrow.
ProductsNew substances produced β right side of the arrow, different properties from reactants.
CoefficientNumber IN FRONT of a formula (e.g. 2 in 2HβO).
SubscriptSmall number AFTER an element symbol (e.g. 2 in HβO).
| Steps to balance an equation |
|---|
| 1. Write the unbalanced equation, checking each formula is correct. |
| 2. List elements on each side. |
| 3. Count atoms of each element on each side. |
| 4. Multiply counts until both sides are equal. |
| 5. Place coefficients in front of formulas. |
| 6. Check: coefficient Γ subscript must match on both sides for every element. |
β Common Mistake: You can change subscripts to balance an equation
β Correct ideaChanging subscripts changes the SUBSTANCE ITSELF (a different compound)! Only COEFFICIENTS (numbers in front) may be changed when balancing.
Definitions Drill: Chemical Reactions
1. Substances that react with each other at the START of a reaction are called ____________.
2. New substances formed at the END of a reaction are called ____________.
3. The number written IN FRONT of a formula (e.g. the 2 in 2HβO) is called a ____________.
4. The small number written AFTER an element symbol (e.g. the 2 in HβO) is called a ____________.
5. To balance an equation you may only change the ____________, never the subscripts.
Practice Questions: Balancing Equations
1. Balanced form of Mg + Oβ β MgO:
2. In 2Hβ + Oβ β 2HβO, oxygen atoms on LEFT side:
3. In a chemical reaction, atoms are conserved but:
4. In 4Aβ + 3Oβ β 2AββOβ, aluminium atoms on RIGHT side:
5. Balanced form of Fe + Oβ β FeβOβ:
6. TRUE statement about balancing equations:
7. Balanced form of Hβ + Clβ β HCl:
8. Coefficients needed for 2KOH + HβSOβ β KβSOβ + ?HβO:
4. Reactions with Oxygen, Combustion & Rusting
CombustionReaction with oxygen during burning β releases heat and light.
Metal + oxygenβ metal oxide (BASE, pH > 7)
Non-metal + oxygenβ non-metal oxide (ACID when dissolved in water, pH < 7)
RustingSLOW reaction of iron with oxygen AND moisture β iron oxide (FeβOβ). Surface only.
GalvanisingCovering iron with zinc to prevent rusting.
| Reaction | Word equation | Balanced equation |
|---|---|---|
| Iron + oxygen | iron + oxygen β iron oxide | 4Fe + 3Oβ β 2FeβOβ |
| Magnesium + oxygen | magnesium + oxygen β magnesium oxide | 2Mg + Oβ β 2MgO |
| Carbon + oxygen | carbon + oxygen β carbon dioxide | C + Oβ β COβ |
| Sulfur + oxygen | sulfur + oxygen β sulfur dioxide | S + Oβ β SOβ |
β Common Mistake: Rusting and combustion are the same process
β Correct ideaCombustion is FAST, releases heat/light. Rusting is SLOW, needs oxygen AND moisture, produces no visible heat/light.
π Ways to prevent rustingPaint the surface Β· Cover with oil/grease Β· Galvanise (zinc coating) Β· Electroplate with chromium/zinc.
Definitions Drill: Combustion, Rusting & Acid Rain
1. The reaction of a substance with oxygen during burning, releasing heat and light, is called ____________.
2. The slow chemical reaction of iron with oxygen AND moisture forming iron oxide is called ____________.
3. Covering iron with a layer of zinc to prevent rusting is called ____________.
4. The general product when a METAL reacts with oxygen is called a ____________.
5. Metal oxides dissolved in water form solutions with pH ____________ 7.
6. Non-metal oxides dissolved in water form solutions with pH ____________ 7.
7. COβ and SOβ dissolved in rainwater produce ____________.
Practice Questions: Oxygen Reactions & Rusting
1. Metal oxide dissolved in water forms a solution that is:
2. Two requirements for rusting:
3. Carbon burning in excess oxygen produces:
4. Non-metal oxide dissolved in water forms a solution that is:
5. Magnesium burning in air produces:
6. Rust only forms at the SURFACE of iron because:
7. Sulfur dioxide dissolving in water contributes to:
8. Which is NOT a way to prevent rusting?
9. Balanced equation for iron burning in oxygen:
10. Non-metal oxides include:
5. Acids, Bases & pH
pHMeasure of how acidic or basic a substance is β scale 1β14.
AcidpH 1β7. Turns blue litmus red; universal indicator β red/orange/yellow.
BasepH 7β14. Turns red litmus blue; universal indicator β blue/purple. Soluble bases = alkalis.
NeutralpH = 7. Universal indicator stays green.
IndicatorChemical that shows (via colour change) if a substance is acid, base, or neutral.
NeutralisationAcid + base reaction β less acidic/basic product.
SaltProduct (other than water) formed when acid reacts with a base.
| General reaction | Products |
|---|---|
| Acid + metal oxide | Salt + water |
| Acid + metal hydroxide | Salt + water |
| Acid + metal carbonate | Salt + COβ + water |
| Acid + metal | Salt + hydrogen |
β Common Mistake: HCl always forms a 'hydrochloride' salt
β Correct ideaHCl β salt ends in '-chloride' (e.g. MgClβ = magnesium chloride). HβSOβ β salt ends in '-sulphate' (e.g. MgSOβ = magnesium sulphate).
Definitions Drill: Acids, Bases & pH
1. The measure of how acidic or basic a substance is (scale 1β14) is called ____________.
2. A chemical that shows (through colour change) whether a substance is acid, base, or neutral is an ____________.
3. The reaction between an acid and a base, producing a more neutral result, is called ____________.
4. A product (other than water) formed when an acid reacts with a base is called a ____________.
5. An indicator that shows the FULL range of pH values through colour changes is called ____________.
6. A soluble base is also called an ____________.
7. A neutral substance has a pH value of ____________.
8. Acids have pH values ____________ (below/above) 7.
9. Bases have pH values ____________ (below/above) 7.
10. The chemical formula for hydrochloric acid is ____________.
11. The chemical formula for sulphuric acid is ____________.
Practice Questions: Acids, Bases & pH
1. A substance with pH 4 is:
2. HCl + MgO β
3. Universal indicator turns GREEN in solution that is:
4. Acid + metal carbonate β
5. Red litmus paper turns BLUE when dipped in a:
6. Blue litmus paper turns RED when dipped in a:
7. HβSOβ + MgO β
8. An example of a STRONG base is:
9. Limestone (CaCOβ) is added to soil to:
10. Vinegar + bicarbonate of soda β gas bubbles of:
11. Acid + metal β
12. A strong acid + weak base results in final pH:
13. Bicarbonate of soda formula:
Short Answer: Acids & Bases
1. Write the balanced chemical equation for the reaction between magnesium oxide and hydrochloric acid.
2HCl + MgO β MgClβ + HβO
2. Write the balanced chemical equation for magnesium oxide reacting with sulphuric acid.
HβSOβ + MgO β MgSOβ + HβO
3. Explain why bicarbonate of soda can calm a bee sting (which is acidic).
Bicarbonate of soda is a base. It neutralises the acidic bee sting substance, raising the pH towards neutral and reducing the burning sensation.
6. Term 2 Mixed Review
A comprehensive mixed set covering everything from Term 2 β great practice before a test!
Term 2 Mixed Review
1. The number of protons in the nucleus is the:
2. COβ has how many atoms per molecule?
3. A substance that turns blue litmus red is:
4. Galvanising is:
5. Formula for sodium hydroxide:
6. Balanced form of C + Oβ β ?
7. Balanced form of Hβ + Clβ β HCl:
8. Best description of a semi-metal:
9. Universal indicator turns blue/purple β pH is likely:
10. Iron reacts slowly with oxygen and moisture β this is called:
11. Formula for ammonium nitrate:
12. Reactants in 2Mg + Oβ β 2MgO are:
13. An atom with 17 protons and 18 neutrons has mass number:
14. Gas produced when acid reacts with metal carbonate:
15. A compound formula starting with NHβ has a name starting with:
π Exam Paper Questions β Matter & Material (from past papers)
π NoteQuestions taken directly from the Grade 9 FS Revision Booklets β Papers A, B & C.
Multiple Choice β Term 2 Exam Style
1. The total number of atoms contained in 5NaHCOβ is β¦
2. A nail submerged in salt water will rust fastest because:
3. Which chemical equation correctly represents the reaction between magnesium hydroxide and hydrochloric acid?
4. Which of these is the most BASIC/ALKALINE household substance? (Bleach pH 13.1, Vinegar pH 3.2, Oven cleaner pH 11.2, Distilled water pH 7.05)
5. Why do beryllium and magnesium appear in the same group on the periodic table?
6. Hydrogen nitrate (HNOβ) consists of which elements?
7. Which one of the following is an example of a compound?
8. Which chemical equation is NOT balanced? (Select the unbalanced one)
9. The elements I, F, Cl, Br have in common that they β¦
10. New substances formed during chemical reactions are called β¦
11. Arrange these pH values from LEAST to MOST acidic: 6, 4, 2, 1
12. When iron wool reacts with pure oxygen in a combustion reaction, the metal oxide formed is called β¦
Fill in the Blank β Term 2 Exam Style
1. The arrangement of all known elements is called the ____________.
2. The process taking place when an acid reacts with a base is called ____________.
3. A substance that changes colour depending on the pH of the solution it is placed in is called an ____________.
4. The reaction of a substance (metal or non-metal) with oxygen is called ____________.
5. The slow chemical reaction of iron with oxygen and moisture is called ____________.
6. The gas produced when sulphur burns in oxygen is called ____________.
7. When iron powder reacts with hydrochloric acid, the gas released is ____________.
8. The gas released when calcium carbonate reacts with hydrochloric acid is ____________.
9. The common name of elements found in Group 18 (VIII) of the periodic table is ____________.
10. Non-metal oxides dissolved in water form ____________ solutions.
Short-Answer / Equation Questions β Term 2 Exam Style
1. Balance the equation: Cu + Oβ β CuO
2Cu + Oβ β 2CuO
2. Write a BALANCED chemical equation for calcium carbonate reacting with hydrochloric acid.
CaCOβ + 2HCl β CaClβ + COβ + HβO
3. Write a balanced equation for sulphuric acid reacting with magnesium hydroxide.
HβSOβ + Mg(OH)β β MgSOβ + 2HβO
4. Write a balanced equation for sulphur burning in pure oxygen.
S + Oβ β SOβ
5. Explain how rust forms on an iron nail.
Rusting is a slow chemical reaction of iron metal with oxygen AND moisture (water) to form iron oxide. Both oxygen and water must be present for rusting to occur.
6. How would you test for carbon dioxide gas in the laboratory?
Bubble the gas through clear lime water. If COβ is present, the clear lime water will turn milky/cloudy.
7. Element X has the notation βΈββX and element Y has ΒΉΒ²ββY. (a) Name element Y. (b) Give the atomic number of Y. (c) Is X a metal, non-metal or semi-metal?
(a) Magnesium (Mg)
(b) Atomic number of Y = 12
(c) X (atomic number 8, oxygen) is a non-metal
(b) Atomic number of Y = 12
(c) X (atomic number 8, oxygen) is a non-metal
8. Name TWO ways in which rust can be prevented.
Any TWO of:
β’ Paint the iron/steel to keep away moisture and oxygen
β’ Coat with chromium or zinc (electroplating/galvanising)
β’ Apply oil or grease
β’ Paint the iron/steel to keep away moisture and oxygen
β’ Coat with chromium or zinc (electroplating/galvanising)
β’ Apply oil or grease
Term 3 β Energy and Change
Score: 0 / 0
1. Forces β Types, Effects & Electrostatics
ForcePush, pull or twist on an object. Measured in newtons (N). Forces act in pairs.
Contact forceResults when two bodies are physically touching (friction, tension, compression).
Field forceActs at a distance β gravitational, magnetic, electrostatic.
Gravitational forceAttraction between objects due to masses. Decreases as distance increases.
MassAmount of matter β constant everywhere (kg).
WeightGravitational force on an object (N). Changes with location. W = m Γ g
Magnetic forceAttraction/repulsion between magnetic materials. Like poles repel; unlike poles attract.
Electrostatic forceForce between charged objects (from friction/electron transfer). Like charges repel; unlike attract.
TensionPulling/stretching contact force (e.g. stretched spring).
CompressionPushing/squashing contact force (e.g. squashed spring).
β Common Mistake: Weight = mass
β Correct ideaMass (kg) = amount of matter, constant everywhere. Weight (N) = gravitational force on that mass, varies by location. W = mass Γ g. Bathroom scales measure WEIGHT but are calibrated to show mass.
β Common Mistake: Protons move during friction-charging
β Correct ideaOnly ELECTRONS transfer between materials when rubbed. Protons are locked in the nucleus. Material gaining electrons β negatively charged. Material losing electrons β positively charged.
Definitions Drill: Forces
1. A push, pull or twist exerted on an object is called a ____________.
2. A force that results when two bodies are TOUCHING is called a ____________.
3. A force that acts at a DISTANCE (no touching needed) is called a ____________.
4. The amount of matter in an object, constant everywhere, is its ____________.
5. The gravitational force exerted on an object by a planet is its ____________.
6. A pulling or stretching contact force is called ____________.
7. A pushing or squashing contact force is called ____________.
8. Force is measured in units called ____________.
9. The attraction between objects/bodies due to their masses is called ____________ force.
10. The force between charged objects, caused by electron transfer through friction, is called ____________ force.
11. A negatively charged object has an ____________ of electrons.
12. A positively charged object has a ____________ of electrons.
Practice Questions: Forces
1. An apple falling from a tree is due to:
2. A negatively charged object has:
3. Gravitational force:
4. Two NORTH poles facing each other will:
5. A positively charged object has:
6. Forces always act in:
7. Stretching a rubber band involves which contact force?
8. Squashing a spring between your hands involves:
9. A balloon rubbed on hair becomes negatively charged because:
10. A positively AND negatively charged object brought close together will:
11. Lightning occurs when:
12. Objects with LARGER mass, same distance apart, have ____________ gravitational force between them.
13. During a thunderstorm, a sensible safety precaution is:
14. Earth pulls on an apple. The apple pulls on Earth too. Comparing these forces:
15. During friction-charging, which particles TRANSFER between materials?
Calculations: Weight & Gravitational Force
1. Calculate the weight of a 3 kg object on Earth. (W = m Γ g, g = 9,8 mΒ·sβ»Β²)
W = 3 kg Γ 9,8 mΒ·sβ»Β² = 29,4 N
2. Calculate the weight of a 10 kg object on Earth.
W = 10 kg Γ 9,8 mΒ·sβ»Β² = 98 N
3. An astronaut has a mass of 80 kg on Earth. What is the astronaut's MASS on the Moon? Explain.
The astronaut's mass is still 80 kg on the Moon β mass does not change with location, only WEIGHT does (because the Moon has weaker gravitational field).
4. A cart (mass 60 kg) is pushed to the right with a force of 120 N. Friction acts at 44 N. Calculate the net horizontal force and state its direction.
Net force = 120 N β 44 N = 76 N to the RIGHT (in the direction of the applied push).
2. Electric Cells & Resistance
Electric currentFlow of charge β measured in amperes (A).
CellChemical reactions β electrical energy for an external circuit.
BatteryTwo or more cells connected together.
ResistanceOpposition to flow of charge β measured in ohms (Ξ©).
Potential differenceMeasured in volts (V) by a voltmeter (connected in PARALLEL).
ResistorConducting material chosen to control current or provide useful energy transfer.
ElectrolyteChemical inside a cell that (with electrodes) allows current to flow.
π 4 factors affecting resistance1) Type of material Β· 2) Thickness (thinner = MORE resistance) Β· 3) Length (longer = MORE resistance) Β· 4) Temperature (hotter = MORE resistance)
Definitions Drill: Cells, Current & Resistance
1. The flow of charge through a conductor is called electric ____________.
2. A system where chemical reactions cause electricity to flow through an external circuit is a ____________.
3. Two or more cells connected together form a ____________.
4. Opposition to the flow of charge is called ____________.
5. Resistance is measured in units called ____________ (Ξ©).
6. Current is measured in units called ____________ (A).
7. Potential difference is measured in units called ____________ (V).
8. A conducting material chosen to control current in a circuit is a ____________.
9. Thinner wires have ____________ resistance than thicker wires.
10. Longer wires have ____________ resistance than shorter wires.
11. Hotter conductors generally have ____________ resistance.
Practice Questions: Cells & Resistance
1. What is resistance?
2. Unit for resistance:
3. A wire is cut in HALF. Resistance of each half vs. original:
4. As temperature increases, resistance generally:
5. Which factor does NOT affect resistance?
6. A THICKER wire has ____________ resistance than a thinner wire.
7. A LONGER wire has ____________ resistance than a shorter wire.
8. A cell converts:
9. For a circuit to work, it must be:
10. LED stands for:
11. In a lemon-battery, the lemon juice acts as the:
12. Removing some lemons from a lemon-battery powering an LED will cause it to:
3. Series & Parallel Circuits
| Series Circuit | Parallel Circuit |
|---|---|
| ONE pathway for current | TWO OR MORE pathways for current |
| Current SAME everywhere: Iβ = Iβ | Total current = sum of branches: I = Iβ + Iβ |
| Voltage SHARED (potential dividers): V_total = Vβ + Vβ | Voltage SAME across each branch (current dividers): Vβ = Vβ |
| Adding resistor β total resistance β β current β | Adding resistor β total resistance β β total current β |
| One bulb fuses β ALL bulbs go off | One bulb fuses β OTHER bulbs stay lit |
AmmeterMeasures current (A). Connected IN SERIES. Very LOW resistance.
VoltmeterMeasures potential difference (V). Connected IN PARALLEL. Very HIGH resistance.
β Common Mistake: Adding more bulbs in parallel makes each bulb dimmer (like in series)
β Correct ideaIn parallel, the voltage across each branch stays the same as the battery voltage β each identical bulb shines with the SAME brightness. The TOTAL current from the battery increases.
Definitions Drill: Circuit Types & Instruments
1. A circuit that provides only ONE pathway for current is a ____________ circuit.
2. A circuit that provides TWO OR MORE pathways for current is a ____________ circuit.
3. In a series circuit, resistors are called '____________' because the total voltage is shared.
4. In a parallel circuit, resistors are called '____________' because the total current is shared.
5. The instrument that measures current, connected IN SERIES, is an ____________.
6. The instrument that measures potential difference, connected IN PARALLEL, is a ____________.
7. An ammeter has very ____________ resistance so it doesn't affect the circuit.
8. A voltmeter has very ____________ resistance so it draws very little current.
Practice Questions: Series & Parallel Circuits
1. Series circuit with 6V battery, 2 identical bulbs β voltage across EACH:
2. In a parallel circuit, if one bulb fuses:
3. Ammeter must be connected:
4. Adding a resistor in PARALLEL causes total resistance to:
5. Adding a resistor in SERIES causes total current to:
6. Voltmeter must be connected:
7. Series circuit: ammeter A1 reads 2A. A2 elsewhere in the SAME series circuit reads:
8. Three 1,5V cells in SERIES β total voltage:
9. Three 1,5V cells in PARALLEL β total voltage:
10. Home lighting circuits are connected in PARALLEL because:
11. In a series circuit, the resistor with HIGHER resistance has:
12. For two resistors in PARALLEL with same voltage, the one with LOWER resistance will have:
13. Parallel circuit: main ammeter reads 6A, two IDENTICAL branches. Each branch ammeter reads:
14. A closed switch:
15. Series circuit with 9V battery, 3 identical resistors β voltage across EACH:
Circuit Calculations
1. In a series circuit, battery voltage (Vβ) = 12V, Vβ = 8V. Find Vβ. Which resistor has the HIGHEST resistance and why?
Vβ = Vβ β Vβ = 12 β 8 = 4V. Resistor connected to Vβ (8V) has the HIGHEST resistance β in a series circuit, higher resistance β larger share of the voltage.
2. Parallel circuit: main ammeter = 10A, Branch 1 ammeter = 4A. Find Branch 2 ammeter reading.
I_total = Iβ + Iβ. So Iβ = 10 β 4 = 6A.
3. Series circuit with 3 identical cells (each 1.5V). Total battery voltage?
V_total = Vβ + Vβ + Vβ = 1,5 + 1,5 + 1,5 = 4,5V.
4. Electricity Generation, Safety & Cost
Power stationSystem for generating electricity (coal-fired, nuclear, hydro, wind).
TurbineSpun by steam/water/wind β drives the generator.
GeneratorConverts mechanical spinning energy β electrical energy.
National gridNetwork distributing electricity at high voltage; transformers step down for consumers (~15% energy lost as heat).
Earth wire3-pin plug safety wire; discharges fault current safely to ground (near-zero resistance).
Fuse / Circuit breakerSafety devices that cut off current if it becomes dangerously high.
kWh1 kilowatt-hour = 1 'unit' of electrical energy.
π Cost formulaCost = Power rating (kW) Γ Hours used (h) Γ Unit price (R/kWh)
π 3-pin plug wiresLIVE (brown) β current to appliance | NEUTRAL (blue) β return path | EARTH (yellow/green) β fault safety
Definitions Drill: Power Generation, Safety & Cost
1. A device spun by steam (or water/wind) that drives a generator is called a ____________.
2. The device that converts spinning mechanical energy into electrical energy is a ____________.
3. The network of power lines distributing electricity at high voltage is called the ____________.
4. The wire in a 3-pin plug that safely carries fault current to the ground is the ____________.
5. A safety device that melts and breaks a circuit if current becomes dangerously high is a ____________.
6. The unit of electrical energy used by consumers (= 1 'unit') is the ____________.
7. The nuclear process releasing heat from radioactive fuel is called nuclear ____________.
8. About ____________% of energy is wasted as heat in the national grid.
Practice Questions: Power Generation, Safety & Cost
1. What directly causes the turbine to rotate in a coal-fired power station?
2. The earth wire in a 3-pin plug:
3. 1 kWh equals:
4. Koeberg in the Cape is a ____________ power station.
5. About ____________% of energy is wasted in the national grid.
6. Nuclear waste is a concern because:
7. A renewable energy source that can drive turbines:
8. Illegal connections to the electricity grid are:
9. The EARTH wire colour in a 3-pin plug is:
10. Overload safety devices in electrical circuits:
Calculations: Cost of Electricity
1. A 2 500W (2,5 kW) dryer runs for 30 min. Electricity costs R2,40/kWh. Calculate the cost.
Time = 30 min = 0,5 h. Units = 2,5 kW Γ 0,5 h = 1,25 kWh. Cost = 1,25 Γ R2,40 = R3,00
2. A 1 400W (1,4 kW) frying pan is used for 4 hours. Electricity costs R1,94/kWh. Calculate the cost.
Units = 1,4 kW Γ 4 h = 5,6 kWh. Cost = 5,6 Γ R1,94 = R10,86
3. A 2 600W (2,6 kW) geyser runs 4,4 h/day. A solar geyser uses 4,42 kWh/day. Electricity costs R1,22/kWh. How much is saved daily?
Electric geyser: 2,6 Γ 4,4 = 11,44 kWh β cost = 11,44 Γ R1,22 = R13,96.
Solar geyser: 4,42 Γ R1,22 = R5,39.
Daily saving = R13,96 β R5,39 = R8,57
Solar geyser: 4,42 Γ R1,22 = R5,39.
Daily saving = R13,96 β R5,39 = R8,57
4. A school has 45 computers, each 120 W. Calculate the total power in kW.
Total = 45 Γ 120 W = 5 400 W = 5,4 kW
5. A 2 kW heater runs for 2,5 hours at R2,00/kWh. Calculate the cost.
Units = 2 kW Γ 2,5 h = 5 kWh. Cost = 5 Γ R2,00 = R10,00
5. Term 3 Mixed Review
A comprehensive mixed set covering everything from Term 3 β great practice before a test!
Term 3 Mixed Review
1. Which is a FIELD (non-contact) force?
2. Mass is measured in:
3. Weight is measured in:
4. Series circuit, 4 bulbs, one fuses. Result:
5. Resistance is measured in:
6. Ammeter has very LOW resistance so:
7. Voltmeter has very HIGH resistance so:
8. A thundercloud becomes charged because:
9. Gravitational force between two planets INCREASES if:
10. Correct order in a coal-fired power station:
11. Magnetic field lines run from:
12. A 2kW heater, 2,5 hours, R2,00/kWh. Cost:
13. Magnetic substances include:
14. Voltage across each branch in a parallel circuit is:
15. Adding resistors in PARALLEL: total resistance:
π Exam Paper Questions β Energy & Change (from past papers)
π NoteQuestions taken directly from the Grade 9 FS Revision Booklet #2 β Papers A, B, C & D.
Multiple Choice β Term 3 Exam Style
1. A negatively charged rod A and a positively charged rod B are brought close together. What will happen?
2. A cricket bat hits a ball at point A. The ball passes point B in the air. The force at A and at B are respectively:
3. A lemon with zinc and copper nails connected to an LED lights it up. The lemon acts as a β¦
4. A battery of four 2 V cells connected in PARALLEL. The voltage across the battery is:
5. Adding a bulb to a series circuit will β¦
6. Which is TRUE about current in a parallel circuit?
7. One unit of electricity is the same as one β¦
8. Which ONE does NOT form part of the national electricity grid?
9. As more resistors are added in SERIES, the total resistance β¦
10. The energy conversion in a cell connected in a closed circuit is from β¦
11. The force that acts when coarse surfaces slide across or rub against each other is β¦
12. The primary energy source used in Eskom coal power plants is β¦
Fill in the Blank β Term 3 Exam Style
1. The characteristic of a conductor that opposes the flow of electric current is called ____________.
2. The giant spark of electricity that occurs between a charged cloud and the ground is called ____________.
3. The subatomic particles that move from a cloud to the ground to create lightning are ____________.
4. The component in the electricity grid that steps voltage up or down is called a ____________.
5. The type of force that exists between charged objects is called an ____________ force.
6. The instrument used to measure current in a circuit is an ____________.
7. The instrument used to measure potential difference (voltage) is a ____________.
8. The unit in which force is measured is the ____________.
9. In a power station, the device that converts mechanical energy into electrical energy is called a ____________.
10. A device used to vary the resistance in a circuit (e.g. inside a stove knob) is called a ____________.
Short-Answer / Calculation Questions β Term 3 Exam Style
1. A refrigerator has a power rating of 200 W. Convert 200 W to kilowatt, then calculate how many hours it can run if R300 of prepaid electricity is bought at R1,80 per kWh.
200 W Γ· 1000 = 0,2 kW
Cost = Power Γ Hours Γ Unit price
300 = 0,2 Γ hours Γ 1,80
Hours = 300 Γ· (0,2 Γ 1,80) = 300 Γ· 0,36 = 833,33 hours
Cost = Power Γ Hours Γ Unit price
300 = 0,2 Γ hours Γ 1,80
Hours = 300 Γ· (0,2 Γ 1,80) = 300 Γ· 0,36 = 833,33 hours
2. A washing machine has a power rating of 480 W and runs for 1,5 hours. Electricity costs R1,65 per kWh. Calculate the cost.
480 W Γ· 1000 = 0,48 kW
Cost = 0,48 Γ 1,5 Γ 1,65 = R1,19
Cost = 0,48 Γ 1,5 Γ 1,65 = R1,19
3. In a SERIES circuit (Circuit A): two cells (each 2 V) are connected in series with two bulbs. Vβ reads 1 V. What is the reading on Vβ (battery voltage) and on Vβ?
Vβ (battery) = 2 + 2 = 4 V
Vβ = 4 β 1 = 3 V
Vβ = 4 β 1 = 3 V
4. Name TWO disadvantages of coal-fired power stations.
Any TWO of:
β’ Burns non-renewable coal that will be exhausted
β’ Causes air pollution / releases greenhouse gases / contributes to global warming
β’ Uses large amounts of water
β’ Causes water and environmental pollution
β’ Burns non-renewable coal that will be exhausted
β’ Causes air pollution / releases greenhouse gases / contributes to global warming
β’ Uses large amounts of water
β’ Causes water and environmental pollution
5. Name TWO factors that affect the resistance of a conductor, and explain HOW each factor affects it.
Length: Longer conductors have higher resistance; shorter conductors have lower resistance.
Thickness/diameter: Thinner conductors have higher resistance; thicker conductors have lower resistance.
Temperature: Higher temperature increases resistance.
Type of material: Different materials have different resistances. (Any TWO)
Thickness/diameter: Thinner conductors have higher resistance; thicker conductors have lower resistance.
Temperature: Higher temperature increases resistance.
Type of material: Different materials have different resistances. (Any TWO)
6. In a PARALLEL circuit, bulb Rβ fuses (burns out). What happens to the ammeter reading? Explain.
The ammeter reading will DECREASE, because removing a parallel branch increases the total resistance of the circuit, which decreases the total current.
7. An investigation tests how the pH of hydrochloric acid affects how fast iron reacts. Write a hypothesis for this investigation.
If the pH of the hydrochloric acid solution decreases (becomes more acidic), then iron will react faster (more mass of iron will dissolve in the same time).
OR: If the pH increases, then the rate of reaction between iron and the acid will decrease.
OR: If the pH increases, then the rate of reaction between iron and the acid will decrease.