▶️ Answer/Explanation
Breathing is the physical act of ventilation, not the official characteristic — respiration is the chemical process, so option A pairs one correct and one incorrect term.
Egestion is removal of undigested food, which is not one of the seven defined characteristics, so option B is wrong.
Movement and sensitivity are both officially defined characteristics of all living organisms.
Photosynthesis is specific to green plants/algae, not all living organisms, ruling out option D.
✅ Answer: (C)
Egestion is removal of undigested food, which is not one of the seven defined characteristics, so option B is wrong.
Movement and sensitivity are both officially defined characteristics of all living organisms.
Photosynthesis is specific to green plants/algae, not all living organisms, ruling out option D.
✅ Answer: (C)
▶️ Answer/Explanation
Animal cells only have a cell membrane and never have a cell wall, so statement 1 is correct and statement 2 is wrong.
Plant cells have both a cell wall and a cell membrane (the membrane lies just inside the wall), so statement 3 is wrong and statement 4 is correct.
The correct pair of true statements is therefore 1 and 4.
✅ Answer: (B)
Plant cells have both a cell wall and a cell membrane (the membrane lies just inside the wall), so statement 3 is wrong and statement 4 is correct.
The correct pair of true statements is therefore 1 and 4.
✅ Answer: (B)
▶️ Answer/Explanation
The test for a reducing sugar uses Benedict’s solution.
The sample is heated with Benedict’s solution in a water bath at around \(95^{\circ}\text{C}\).
A positive result is a colour change from blue to a brick-red precipitate.
The row in the table that correctly pairs “Benedict’s solution” with “heat” gives the correct reagent/condition combination.
✅ Answer: (A)
The sample is heated with Benedict’s solution in a water bath at around \(95^{\circ}\text{C}\).
A positive result is a colour change from blue to a brick-red precipitate.
The row in the table that correctly pairs “Benedict’s solution” with “heat” gives the correct reagent/condition combination.
✅ Answer: (A)
▶️ Answer/Explanation
Below the optimum temperature, rising temperature gives molecules more kinetic energy.
More kinetic energy means more frequent, successful collisions between enzyme and substrate.
This causes the rate of reaction to rise as the temperature rises over the \(10^{\circ}\text{C}\) to \(30^{\circ}\text{C}\) range, before denaturation later reduces it.
✅ Answer: (D)
More kinetic energy means more frequent, successful collisions between enzyme and substrate.
This causes the rate of reaction to rise as the temperature rises over the \(10^{\circ}\text{C}\) to \(30^{\circ}\text{C}\) range, before denaturation later reduces it.
✅ Answer: (D)
▶️ Answer/Explanation
The word equation for photosynthesis is \(\text{carbon dioxide} + \text{water} \rightarrow \text{glucose} + \text{oxygen}\).
Carbon dioxide and water are the raw materials (reactants), not the products.
Glucose and oxygen are the two substances made by the plant, so they are the products.
✅ Answer: (C)
Carbon dioxide and water are the raw materials (reactants), not the products.
Glucose and oxygen are the two substances made by the plant, so they are the products.
✅ Answer: (C)
▶️ Answer/Explanation
In the lower jaw, teeth are arranged from front to back as incisors, then canine, then premolars, then molars.
Tooth X is positioned in the row at the broad, ridged double-cusped tooth located between the canine and the molars.
This shape and position identify it as a premolar.
✅ Answer: (D)
Tooth X is positioned in the row at the broad, ridged double-cusped tooth located between the canine and the molars.
This shape and position identify it as a premolar.
✅ Answer: (D)
▶️ Answer/Explanation
Dye dissolved in water is taken up by the cut stem in the same way as water and mineral ions normally would be.
Water and dissolved substances move upward through the stem exclusively in the xylem vessels.
The dye therefore travels up the xylem and stains the petals at the top.
✅ Answer: (D)
Water and dissolved substances move upward through the stem exclusively in the xylem vessels.
The dye therefore travels up the xylem and stains the petals at the top.
✅ Answer: (D)
▶️ Answer/Explanation
During exercise, muscles respire faster and need more oxygen delivered and more carbon dioxide removed.
This means breathing rate increases and heart rate increases at the same time.
The correct row is the one in which both breathing rate and heart rate increase together.
✅ Answer: (A)
This means breathing rate increases and heart rate increases at the same time.
The correct row is the one in which both breathing rate and heart rate increase together.
✅ Answer: (A)
▶️ Answer/Explanation
Adrenaline is released by the adrenal glands in stressful or “fight or flight” situations such as fear, excitement or danger.
Calm, routine activities with no element of stress or excitement do not trigger extra adrenaline release.
The correct activities are those representing sudden stress, excitement or danger, matching the listed option.
✅ Answer: (A)
Calm, routine activities with no element of stress or excitement do not trigger extra adrenaline release.
The correct activities are those representing sudden stress, excitement or danger, matching the listed option.
✅ Answer: (A)
▶️ Answer/Explanation
Germination requires water to activate enzymes and oxygen for aerobic respiration to release energy.
Light is not a requirement for germination itself, only for the seedling’s later growth by photosynthesis.
The results show seeds germinated whenever water and oxygen were present, regardless of light.
✅ Answer: (C)
Light is not a requirement for germination itself, only for the seedling’s later growth by photosynthesis.
The results show seeds germinated whenever water and oxygen were present, regardless of light.
✅ Answer: (C)
▶️ Answer/Explanation
Let \(R\) = red (dominant) and \(r\) = yellow (recessive).
The heterozygous red parent is \(Rr\) and the homozygous yellow parent is \(rr\).
The cross \(Rr \times rr\) gives offspring genotypes \(Rr, Rr, rr, rr\), a 1:1 ratio.
This means 50% of offspring are red (\(Rr\)) and 50% are yellow (\(rr\)).
✅ Answer: (B)
The heterozygous red parent is \(Rr\) and the homozygous yellow parent is \(rr\).
The cross \(Rr \times rr\) gives offspring genotypes \(Rr, Rr, rr, rr\), a 1:1 ratio.
This means 50% of offspring are red (\(Rr\)) and 50% are yellow (\(rr\)).
✅ Answer: (B)
▶️ Answer/Explanation
A producer makes its own organic nutrients using light energy through photosynthesis.
A consumer gets its energy by feeding on other organisms, and a decomposer gets its energy from dead or waste organic material.
Only one row in the table pairs an organism type with its precisely correct definition, with the others mixing up these roles.
✅ Answer: (D)
A consumer gets its energy by feeding on other organisms, and a decomposer gets its energy from dead or waste organic material.
Only one row in the table pairs an organism type with its precisely correct definition, with the others mixing up these roles.
✅ Answer: (D)
▶️ Answer/Explanation
Photosynthesis removes carbon dioxide from the air, while respiration and combustion both release carbon dioxide into the air.
Decomposition releases carbon dioxide as decomposers respire while breaking down dead matter.
Only one row correctly states both the process named and whether it adds or removes atmospheric carbon dioxide.
✅ Answer: (B)
Decomposition releases carbon dioxide as decomposers respire while breaking down dead matter.
Only one row correctly states both the process named and whether it adds or removes atmospheric carbon dioxide.
✅ Answer: (B)
▶️ Answer/Explanation
A balance is essential to record the decreasing mass of the flask and its contents as carbon dioxide escapes.
A stop-clock is essential to record the time at which each mass reading is taken.
Pipettes and thermometers are not needed, since volume transfer and temperature are not being measured here.
✅ Answer: (B)
A stop-clock is essential to record the time at which each mass reading is taken.
Pipettes and thermometers are not needed, since volume transfer and temperature are not being measured here.
✅ Answer: (B)
▶️ Answer/Explanation
Burning a wooden splint converts the wood into new substances such as carbon dioxide, water and ash — a chemical change.
Dissolving, evaporating and distilling are all physical changes because no new substance is formed and the change is reversible.
Only burning permanently produces different chemical substances, so it is the chemical change.
✅ Answer: (A)
Dissolving, evaporating and distilling are all physical changes because no new substance is formed and the change is reversible.
Only burning permanently produces different chemical substances, so it is the chemical change.
✅ Answer: (A)
▶️ Answer/Explanation
NaOH contains three different elements: sodium (Na), oxygen (O) and hydrogen (H).
Rb\(_{2}\)S, SiCl\(_{4}\) and SnO\(_{2}\) each contain only two different elements, regardless of how many atoms of each are present.
Counting unique element symbols, not subscript numbers, shows NaOH has the most distinct elements.
✅ Answer: (A)
Rb\(_{2}\)S, SiCl\(_{4}\) and SnO\(_{2}\) each contain only two different elements, regardless of how many atoms of each are present.
Counting unique element symbols, not subscript numbers, shows NaOH has the most distinct elements.
✅ Answer: (A)
▶️ Answer/Explanation
In dilute sulfuric acid, the ions present in greatest relevant concentration for discharge are \(H^{+}\) and \(OH^{-}\) (from water).
At the cathode, \(H^{+}\) ions gain electrons to form hydrogen gas.
At the anode, \(OH^{-}\) ions lose electrons to form oxygen gas and water; sulfate ions are not discharged.
✅ Answer: (B)
At the cathode, \(H^{+}\) ions gain electrons to form hydrogen gas.
At the anode, \(OH^{-}\) ions lose electrons to form oxygen gas and water; sulfate ions are not discharged.
✅ Answer: (B)
▶️ Answer/Explanation
Reaction 1 takes in heat from the surroundings, so it is endothermic, and the surrounding temperature falls.
Reaction 2 releases heat to the surroundings, so it is exothermic, and the surrounding temperature rises.
The correct row labels reaction 1 as endothermic (temperature decrease) and reaction 2 as exothermic (temperature increase).
✅ Answer: (B)
Reaction 2 releases heat to the surroundings, so it is exothermic, and the surrounding temperature rises.
The correct row labels reaction 1 as endothermic (temperature decrease) and reaction 2 as exothermic (temperature increase).
✅ Answer: (B)
▶️ Answer/Explanation
Diluting the acid with water lowers the acid concentration, which reduces collision frequency and slows the reaction.
Using larger lumps of magnesium carbonate gives a smaller surface area, which also reduces collision frequency and slows the reaction.
The slowest experiment is the one combining both the most dilute acid and the largest (least reactive) particle size.
✅ Answer: (C)
Using larger lumps of magnesium carbonate gives a smaller surface area, which also reduces collision frequency and slows the reaction.
The slowest experiment is the one combining both the most dilute acid and the largest (least reactive) particle size.
✅ Answer: (C)
▶️ Answer/Explanation
A reactive metal reacting with a dilute acid always produces a salt plus hydrogen gas.
Here magnesium reacts with hydrochloric acid to give the salt magnesium chloride and hydrogen gas, with no carbon-containing or extra water product.
The word equation is \(\text{magnesium} + \text{hydrochloric acid} \rightarrow \text{magnesium chloride} + \text{hydrogen}\).
✅ Answer: (A)
Here magnesium reacts with hydrochloric acid to give the salt magnesium chloride and hydrogen gas, with no carbon-containing or extra water product.
The word equation is \(\text{magnesium} + \text{hydrochloric acid} \rightarrow \text{magnesium chloride} + \text{hydrogen}\).
✅ Answer: (A)
▶️ Answer/Explanation
Carbon dioxide turns limewater milky/cloudy because an insoluble calcium carbonate precipitate forms.
Chloride ions with silver nitrate give a white precipitate, and copper(II) ions with sodium hydroxide give a blue precipitate.
Reacting a carbonate with dilute hydrochloric acid simply releases carbon dioxide gas and forms a soluble salt solution, with no precipitate.
✅ Answer: (B)
Chloride ions with silver nitrate give a white precipitate, and copper(II) ions with sodium hydroxide give a blue precipitate.
Reacting a carbonate with dilute hydrochloric acid simply releases carbon dioxide gas and forms a soluble salt solution, with no precipitate.
✅ Answer: (B)
▶️ Answer/Explanation
Halogens actually become darker in colour down the group (chlorine pale yellow-green, bromine red-brown, iodine grey-black), so option A is wrong.
They are not all gases at room temperature — bromine is a liquid and iodine is a solid — and they belong to the same group (a column), not the same period, ruling out B and C.
Each halogen exists as a diatomic molecule, e.g. \(\text{Cl}_{2}\), \(\text{Br}_{2}\), \(\text{I}_{2}\), which is the correct statement.
✅ Answer: (D)
They are not all gases at room temperature — bromine is a liquid and iodine is a solid — and they belong to the same group (a column), not the same period, ruling out B and C.
Each halogen exists as a diatomic molecule, e.g. \(\text{Cl}_{2}\), \(\text{Br}_{2}\), \(\text{I}_{2}\), which is the correct statement.
✅ Answer: (D)
▶️ Answer/Explanation
In the blast furnace, carbon (as coke) burns to form carbon monoxide.
Carbon monoxide then removes oxygen from iron(III) oxide: \(\text{Fe}_2\text{O}_3 + 3\text{CO} \rightarrow 2\text{Fe} + 3\text{CO}_2\).
This is a reduction reaction (loss of oxygen from the iron compound), using carbon/carbon monoxide as the reducing agent.
✅ Answer: (D)
Carbon monoxide then removes oxygen from iron(III) oxide: \(\text{Fe}_2\text{O}_3 + 3\text{CO} \rightarrow 2\text{Fe} + 3\text{CO}_2\).
This is a reduction reaction (loss of oxygen from the iron compound), using carbon/carbon monoxide as the reducing agent.
✅ Answer: (D)
▶️ Answer/Explanation
Clean air is approximately 21% oxygen by volume.
Let the total volume be \(V\); then \(0.21 \times V = 10.5\), so \(V = \dfrac{10.5}{0.21} = 50\).
A volume of 50 cm\(^{3}\) of clean air contains 10.5 cm\(^{3}\) of oxygen.
✅ Answer: (C)
Let the total volume be \(V\); then \(0.21 \times V = 10.5\), so \(V = \dfrac{10.5}{0.21} = 50\).
A volume of 50 cm\(^{3}\) of clean air contains 10.5 cm\(^{3}\) of oxygen.
✅ Answer: (C)
▶️ Answer/Explanation
Heating (thermally decomposing) limestone produces lime (calcium oxide): \(\text{CaCO}_3 \rightarrow \text{CaO} + \text{CO}_2\), so statement 3 is correct.
Lime is alkaline and is used to neutralise acidic industrial waste, so statement 4 is also correct.
Limestone/lime is used to increase (not decrease) soil pH, and is not itself classed as a fertilizer, ruling out statements 1 and 2.
✅ Answer: (D)
Lime is alkaline and is used to neutralise acidic industrial waste, so statement 4 is also correct.
Limestone/lime is used to increase (not decrease) soil pH, and is not itself classed as a fertilizer, ruling out statements 1 and 2.
✅ Answer: (D)
▶️ Answer/Explanation
Each fraction of petroleum has one specific named use: refinery gas for heating/cooking, petrol for cars, diesel for diesel engines, and bitumen for roads.
Mixing up these pairings (e.g. bitumen for cars) gives an incorrect row.
Only one row pairs each named fraction with its genuinely correct industrial use.
✅ Answer: (D)
Mixing up these pairings (e.g. bitumen for cars) gives an incorrect row.
Only one row pairs each named fraction with its genuinely correct industrial use.
✅ Answer: (D)
▶️ Answer/Explanation
A polymer is, by definition, a very large molecule built from many smaller repeating units called monomers.
In addition polymerisation, small monomer molecules (such as ethene) join together with no other product formed.
This joining produces one large polymer chain, e.g. poly(ethene), from the many small monomers.
✅ Answer: (C)
In addition polymerisation, small monomer molecules (such as ethene) join together with no other product formed.
This joining produces one large polymer chain, e.g. poly(ethene), from the many small monomers.
✅ Answer: (C)
▶️ Answer/Explanation
Weight and mass are linked by \(g = \dfrac{W}{m}\), so rearranged this gives \(m = \dfrac{W}{g}\).
Substituting the given values: \(m = \dfrac{2.0}{10}\).
This gives \(m = 0.20\ \text{kg}\).
✅ Answer: (B)
Substituting the given values: \(m = \dfrac{2.0}{10}\).
This gives \(m = 0.20\ \text{kg}\).
✅ Answer: (B)
▶️ Answer/Explanation
An object is more stable when its centre of mass X is positioned lower and the line down from X stays well within the base.
A lower centre of mass means the container has to be tilted further before X passes outside the base, so it is harder to topple.
The container with the lowest-positioned centre of mass X is therefore the most stable.
✅ Answer: (D)
A lower centre of mass means the container has to be tilted further before X passes outside the base, so it is harder to topple.
The container with the lowest-positioned centre of mass X is therefore the most stable.
✅ Answer: (D)
▶️ Answer/Explanation
Work done is calculated using \(W = F \times d\), where \(F\) is the force applied and \(d\) is the distance moved in the direction of the force.
Only quantities that appear in this equation — the size of the force and the distance moved — change the value of the work done.
Quantities such as time taken or the box’s mass do not appear in the work equation, so they do not directly affect work done.
✅ Answer: (A)
Only quantities that appear in this equation — the size of the force and the distance moved — change the value of the work done.
Quantities such as time taken or the box’s mass do not appear in the work equation, so they do not directly affect work done.
✅ Answer: (A)
▶️ Answer/Explanation
Moving air has kinetic energy, which turns the turbine blades.
The spinning blades drive a generator, which is the part of the system that produces electrical energy.
The useful overall transfer is therefore from kinetic energy (of the wind/blades) to electrical energy.
✅ Answer: (C)
The spinning blades drive a generator, which is the part of the system that produces electrical energy.
The useful overall transfer is therefore from kinetic energy (of the wind/blades) to electrical energy.
✅ Answer: (C)
▶️ Answer/Explanation
Solid to liquid is called melting, and liquid to solid is called freezing.
Liquid to gas is called boiling or evaporating, and gas to liquid is called condensing.
Only one row in the table assigns these five terms to the correct state changes without swapping any of them.
✅ Answer: (B)
Liquid to gas is called boiling or evaporating, and gas to liquid is called condensing.
Only one row in the table assigns these five terms to the correct state changes without swapping any of them.
✅ Answer: (B)
▶️ Answer/Explanation
Water heated near the bottom of the system expands and becomes less dense than the surrounding cooler water.
This warmer, less dense water rises, while cooler, denser water sinks to take its place, setting up a convection current.
The correct diagram shows water rising above the heat source and sinking back down elsewhere to form a continuous loop.
✅ Answer: (A)
This warmer, less dense water rises, while cooler, denser water sinks to take its place, setting up a convection current.
The correct diagram shows water rising above the heat source and sinking back down elsewhere to form a continuous loop.
✅ Answer: (A)
▶️ Answer/Explanation
One full wavelength is the distance between two consecutive identical points on the wave, such as crest to crest.
Counting the crests and troughs shown between X and Y in the diagram corresponds to one and a half complete wave cycles.
Therefore the distance from X to Y spans \(1\dfrac{1}{2}\) wavelengths.
✅ Answer: (C)
Counting the crests and troughs shown between X and Y in the diagram corresponds to one and a half complete wave cycles.
Therefore the distance from X to Y spans \(1\dfrac{1}{2}\) wavelengths.
✅ Answer: (C)
▶️ Answer/Explanation
The resistance equation \(R = \dfrac{V}{I}\) can be rearranged to \(V = IR\).
Substituting the given values: \(V = 0.20 \times 0.50\).
This gives \(V = 0.10\ \text{V}\) across the resistor.
✅ Answer: (A)
Substituting the given values: \(V = 0.20 \times 0.50\).
This gives \(V = 0.10\ \text{V}\) across the resistor.
✅ Answer: (A)
▶️ Answer/Explanation
In a parallel arrangement, the branch with the smaller resistance R carries the larger share of the current, so its ammeter reads the higher value.
The combined resistance of resistors R and 2R in parallel is found from \(\dfrac{1}{R_{total}} = \dfrac{1}{R} + \dfrac{1}{2R}\), giving \(R_{total} = \dfrac{2R}{3}\).
This combined resistance is always smaller than the smallest individual resistor, R.
✅ Answer: (C)
The combined resistance of resistors R and 2R in parallel is found from \(\dfrac{1}{R_{total}} = \dfrac{1}{R} + \dfrac{1}{2R}\), giving \(R_{total} = \dfrac{2R}{3}\).
This combined resistance is always smaller than the smallest individual resistor, R.
✅ Answer: (C)
▶️ Answer/Explanation
To gradually increase the current, the circuit needs a variable resistor in series with the fuse to control current smoothly.
An ammeter in series with the fuse is also needed to read off the exact current at the moment the fuse blows.
Only one diagram includes both the fuse, a variable resistor and an ammeter correctly connected in series in a complete circuit.
✅ Answer: (D)
An ammeter in series with the fuse is also needed to read off the exact current at the moment the fuse blows.
Only one diagram includes both the fuse, a variable resistor and an ammeter correctly connected in series in a complete circuit.
✅ Answer: (D)
▶️ Answer/Explanation
The magnetic field around a straight current-carrying wire forms concentric circles centred on the wire.
The direction of these field circles is given by the right-hand grip rule: thumb pointing along the current, fingers curling in the field direction.
Only one diagram shows both the correct concentric-circle pattern and the field direction consistent with the shown current direction.
✅ Answer: (D)
The direction of these field circles is given by the right-hand grip rule: thumb pointing along the current, fingers curling in the field direction.
Only one diagram shows both the correct concentric-circle pattern and the field direction consistent with the shown current direction.
✅ Answer: (D)
▶️ Answer/Explanation
The mass number A counts all nucleons (protons + neutrons), while the atomic number Z counts only protons.
Subtracting A − Z removes the proton count, leaving only the neutrons.
Therefore \(A – Z\) is equal to the number of neutrons in the nucleus.
✅ Answer: (B)
Subtracting A − Z removes the proton count, leaving only the neutrons.
Therefore \(A – Z\) is equal to the number of neutrons in the nucleus.
✅ Answer: (B)
▶️ Answer/Explanation
The activity falls from 2000 to 250, which is a factor of 8, i.e. \(2000 \rightarrow 1000 \rightarrow 500 \rightarrow 250\), three halvings.
Three half-lives have therefore passed in the 30 minutes given.
Dividing the total time by the number of half-lives: \(\dfrac{30}{3} = 10\) minutes.
✅ Answer: (B)
Three half-lives have therefore passed in the 30 minutes given.
Dividing the total time by the number of half-lives: \(\dfrac{30}{3} = 10\) minutes.
✅ Answer: (B)