▶️ Answer/Explanation
Soya seeds are rich in protein, which is an essential nutrient for building and repairing body tissues.
Protein is required for the synthesis of new cells and tissues, making it directly linked to the characteristic of growth.
Excretion, movement, and sensitivity do not depend on protein intake in this context.
✅ Answer: (B)
Protein is required for the synthesis of new cells and tissues, making it directly linked to the characteristic of growth.
Excretion, movement, and sensitivity do not depend on protein intake in this context.
✅ Answer: (B)
▶️ Answer/Explanation
In osmosis, water moves from a region of lower solute concentration (higher water potential) to a region of higher solute concentration (lower water potential) through a semi-permeable membrane.
In a high-concentration sucrose solution, water leaves the potato cells by osmosis, causing the cells to lose turgor pressure and become flaccid (shrunken and soft).
The highest sucrose concentration (option D) would cause the greatest water loss, making the potato pieces the most flaccid.
✅ Answer: (D)
In a high-concentration sucrose solution, water leaves the potato cells by osmosis, causing the cells to lose turgor pressure and become flaccid (shrunken and soft).
The highest sucrose concentration (option D) would cause the greatest water loss, making the potato pieces the most flaccid.
✅ Answer: (D)
▶️ Answer/Explanation
Starch is detected using iodine solution (turns blue-black if positive), protein is detected using the Biuret reagent (turns purple/violet if positive), and reducing sugars are detected using Benedict’s solution (turns brick-red/orange if positive).
The food that gives a positive result for starch and protein but a negative result for reducing sugar must be identified from the table — this corresponds to food B.
✅ Answer: (B)
The food that gives a positive result for starch and protein but a negative result for reducing sugar must be identified from the table — this corresponds to food B.
✅ Answer: (B)
▶️ Answer/Explanation
The graph shows the shortest time (fastest reaction) at pH 5–6, confirming that the optimum pH is between 5 and 6 — so statement 1 is correct.
Statement 2 is incorrect: increased molecular speed with rising temperature explains faster reactions, but pH changes do not directly cause enzyme or substrate molecules to move faster — pH affects the shape of the active site, not molecular speed.
Statement 3 is correct: above the optimum pH, the change in \([\text{H}^+]\) concentration alters the ionic interactions within the enzyme, distorting the shape of the active site and reducing enzyme activity (denaturation).
✅ Answer: (C)
Statement 2 is incorrect: increased molecular speed with rising temperature explains faster reactions, but pH changes do not directly cause enzyme or substrate molecules to move faster — pH affects the shape of the active site, not molecular speed.
Statement 3 is correct: above the optimum pH, the change in \([\text{H}^+]\) concentration alters the ionic interactions within the enzyme, distorting the shape of the active site and reducing enzyme activity (denaturation).
✅ Answer: (C)
▶️ Answer/Explanation
Magnesium ions (\(\text{Mg}^{2+}\)) are an essential component of the chlorophyll molecule; without sufficient magnesium, the plant cannot synthesise enough chlorophyll.
A deficiency of chlorophyll causes leaves to turn yellow, a condition known as chlorosis.
While reduced photosynthesis is a consequence of chlorosis, it is not the direct cause — the root cause is the lack of magnesium needed to make chlorophyll.
✅ Answer: (A)
A deficiency of chlorophyll causes leaves to turn yellow, a condition known as chlorosis.
While reduced photosynthesis is a consequence of chlorosis, it is not the direct cause — the root cause is the lack of magnesium needed to make chlorophyll.
✅ Answer: (A)
▶️ Answer/Explanation
Dietary fibre (roughage) consists of indigestible plant material, mainly cellulose, that adds bulk to food in the large intestine.
This bulk stimulates peristalsis — the muscular contractions that move food through the gut — helping to prevent constipation.
Carbohydrates, fats, and proteins provide energy or structural materials but do not directly stimulate gut movement in the same way.
✅ Answer: (D)
This bulk stimulates peristalsis — the muscular contractions that move food through the gut — helping to prevent constipation.
Carbohydrates, fats, and proteins provide energy or structural materials but do not directly stimulate gut movement in the same way.
✅ Answer: (D)
▶️ Answer/Explanation
In year 1, the plant stores food (mainly carbohydrates) in its large root, so the root grows and is filled with stored food reserves.
In year 2, the plant uses the stored food in the root to fuel the growth of flowers and seeds for reproduction, so the root shrinks as the reserves are used up.
This means in year 1 the root is growing/storing, and in year 2 the root is shrinking/losing stored food — corresponding to row B.
✅ Answer: (B)
In year 2, the plant uses the stored food in the root to fuel the growth of flowers and seeds for reproduction, so the root shrinks as the reserves are used up.
This means in year 1 the root is growing/storing, and in year 2 the root is shrinking/losing stored food — corresponding to row B.
✅ Answer: (B)
▶️ Answer/Explanation
Bread making relies on yeast, which carries out anaerobic respiration (fermentation) in the absence of oxygen.
During fermentation, yeast converts glucose into ethanol and carbon dioxide: \(\text{glucose} \rightarrow \text{ethanol} + \text{carbon dioxide}\).
The carbon dioxide gas produced causes the bread dough to rise (expand), giving bread its light, airy texture.
✅ Answer: (C)
During fermentation, yeast converts glucose into ethanol and carbon dioxide: \(\text{glucose} \rightarrow \text{ethanol} + \text{carbon dioxide}\).
The carbon dioxide gas produced causes the bread dough to rise (expand), giving bread its light, airy texture.
✅ Answer: (C)
▶️ Answer/Explanation
Involuntary actions are those not under conscious control — they are controlled by the autonomic nervous system or occur as reflexes.
Pupil dilation in dim light (statement 1) and increasing heart rate during exercise (statement 2) are both automatic responses not consciously controlled, so they are involuntary.
Picking up a pencil (statement 3) is a deliberate, conscious action controlled by the brain — making it a voluntary action.
✅ Answer: (B)
Pupil dilation in dim light (statement 1) and increasing heart rate during exercise (statement 2) are both automatic responses not consciously controlled, so they are involuntary.
Picking up a pencil (statement 3) is a deliberate, conscious action controlled by the brain — making it a voluntary action.
✅ Answer: (B)
▶️ Answer/Explanation
In a typical flower, the anther (part of the stamen) produces pollen, the filament is the stalk supporting the anther, and the stigma is the sticky top of the carpel that receives pollen during pollination.
By identifying the positions of structures P, Q, and R in the diagram — with P at the pollen-producing top, Q as the supporting stalk, and R as the receptive sticky surface — the correct row is A.
✅ Answer: (A)
By identifying the positions of structures P, Q, and R in the diagram — with P at the pollen-producing top, Q as the supporting stalk, and R as the receptive sticky surface — the correct row is A.
✅ Answer: (A)
▶️ Answer/Explanation
Artificial selection begins by identifying individuals with a desirable characteristic (step 4), then selecting and breeding those individuals together (step 2), allowing the offspring to be born (step 1), and finally selecting the offspring with the most desirable traits to breed again (step 3).
This cycle is repeated over many generations to gradually enhance the desired characteristic in the population.
The correct sequence is therefore 4 → 2 → 1 → 3.
✅ Answer: (D)
This cycle is repeated over many generations to gradually enhance the desired characteristic in the population.
The correct sequence is therefore 4 → 2 → 1 → 3.
✅ Answer: (D)
▶️ Answer/Explanation
Herbivores are organisms that eat only plants (producers); since they obtain energy by consuming another organism, they are by definition consumers.
Statement A is false — carnivores eat animals, not produce; statement B is false — consumers include herbivores and omnivores too; statement D is false — producers are plants, not herbivores.
Statement C is the only universally true statement: every herbivore consumes another organism (plants) and is therefore a consumer.
✅ Answer: (C)
Statement A is false — carnivores eat animals, not produce; statement B is false — consumers include herbivores and omnivores too; statement D is false — producers are plants, not herbivores.
Statement C is the only universally true statement: every herbivore consumes another organism (plants) and is therefore a consumer.
✅ Answer: (C)
▶️ Answer/Explanation
Fertiliser run-off causes rapid algal growth (algal bloom), which blocks sunlight, killing underwater plants; the dead algae and plants are then broken down by aerobic decomposers (bacteria).
The decomposers use up the dissolved oxygen in the water through their aerobic respiration, causing oxygen levels to fall dramatically — this is called deoxygenation.
Fish and other aquatic organisms die because there is insufficient dissolved oxygen for their own aerobic respiration.
✅ Answer: (D)
The decomposers use up the dissolved oxygen in the water through their aerobic respiration, causing oxygen levels to fall dramatically — this is called deoxygenation.
Fish and other aquatic organisms die because there is insufficient dissolved oxygen for their own aerobic respiration.
✅ Answer: (D)
▶️ Answer/Explanation
Isotopes are defined as atoms of the same element that have the same number of protons but different numbers of neutrons; the number of protons determines the element’s identity (atomic number).
Particles W and Y share the same number of protons (making them the same element) but differ in their number of neutrons, satisfying the definition of isotopes.
✅ Answer: (B)
Particles W and Y share the same number of protons (making them the same element) but differ in their number of neutrons, satisfying the definition of isotopes.
✅ Answer: (B)
▶️ Answer/Explanation
The molar mass of methane (\(\text{CH}_4\)) is \(12 + 4 = 16 \text{ g/mol}\), so 16.0 g = 1 mole, which occupies 24 dm³ at r.t.p.
Therefore, 4.0 g of methane = \(\dfrac{4.0}{16.0} = 0.25\) mol.
Volume = \(0.25 \times 24 = 6.0 \text{ dm}^3\).
✅ Answer: (B)
Therefore, 4.0 g of methane = \(\dfrac{4.0}{16.0} = 0.25\) mol.
Volume = \(0.25 \times 24 = 6.0 \text{ dm}^3\).
✅ Answer: (B)
▶️ Answer/Explanation
In electrolysis, the electrolyte is the substance that conducts electricity in its molten or dissolved state — here, molten lead(II) bromide is the electrolyte.
At the cathode (negative electrode), \(\text{Pb}^{2+}\) ions are reduced to form a grey solid of lead metal; at the anode (positive electrode), \(\text{Br}^-\) ions are oxidised to produce orange-brown bromine fumes.
Statement C is correct; A and B are false (bromine forms at the positive anode, not the negative electrode), and D is false (the grey solid is elemental lead, not lead(II) bromide).
✅ Answer: (C)
At the cathode (negative electrode), \(\text{Pb}^{2+}\) ions are reduced to form a grey solid of lead metal; at the anode (positive electrode), \(\text{Br}^-\) ions are oxidised to produce orange-brown bromine fumes.
Statement C is correct; A and B are false (bromine forms at the positive anode, not the negative electrode), and D is false (the grey solid is elemental lead, not lead(II) bromide).
✅ Answer: (C)
▶️ Answer/Explanation
In an exothermic reaction, the energy of the products is lower than the energy of the reactants, so the overall energy change \(\Delta H\) is negative; the diagram must show products at a lower energy level than reactants.
The activation energy is the energy difference between the reactants’ energy level and the peak (transition state) of the energy profile curve.
Diagram C correctly shows: products at a lower level than reactants (exothermic) and the activation energy arrow pointing from reactants up to the peak of the curve.
✅ Answer: (C)
The activation energy is the energy difference between the reactants’ energy level and the peak (transition state) of the energy profile curve.
Diagram C correctly shows: products at a lower level than reactants (exothermic) and the activation energy arrow pointing from reactants up to the peak of the curve.
✅ Answer: (C)
▶️ Answer/Explanation
The apparatus shown collects gas produced by a reaction (gas syringe or inverted measuring cylinder over water), which is used to measure the volume of gas over time.
Reaction C (\(\text{MgCO}_3 + 2\text{HCl}\)) takes place in aqueous solution at room temperature and produces \(\text{CO}_2\) gas that can be collected and measured with this apparatus.
Reactions A and B require high temperatures (not suitable for this apparatus), and reaction D is a displacement reaction in solution producing no gas.
✅ Answer: (C)
Reaction C (\(\text{MgCO}_3 + 2\text{HCl}\)) takes place in aqueous solution at room temperature and produces \(\text{CO}_2\) gas that can be collected and measured with this apparatus.
Reactions A and B require high temperatures (not suitable for this apparatus), and reaction D is a displacement reaction in solution producing no gas.
✅ Answer: (C)
▶️ Answer/Explanation
In this displacement reaction, magnesium atoms (\(\text{Mg}\)) lose two electrons each to form \(\text{Mg}^{2+}\) ions: \(\text{Mg} \rightarrow \text{Mg}^{2+} + 2e^-\).
According to the OIL RIG rule — Oxidation Is Loss (of electrons), Reduction Is Gain (of electrons) — losing electrons means magnesium is oxidised.
✅ Answer: (B)
According to the OIL RIG rule — Oxidation Is Loss (of electrons), Reduction Is Gain (of electrons) — losing electrons means magnesium is oxidised.
✅ Answer: (B)
▶️ Answer/Explanation
To prepare a soluble salt such as cobalt(II) sulfate, the standard method is: react dilute sulfuric acid with an insoluble reactant in excess, then filter to remove the unreacted solid, and evaporate the filtrate to crystallise the salt.
Cobalt(II) carbonate is insoluble, so it can be added in excess to dilute \(\text{H}_2\text{SO}_4\); the excess carbonate is removed by filtration, and the filtrate is evaporated to yield solid cobalt(II) sulfate.
Option A would not work because both reactants are soluble (no precipitate forms and no simple separation is possible); options B and C are also flawed in their procedures.
✅ Answer: (D)
Cobalt(II) carbonate is insoluble, so it can be added in excess to dilute \(\text{H}_2\text{SO}_4\); the excess carbonate is removed by filtration, and the filtrate is evaporated to yield solid cobalt(II) sulfate.
Option A would not work because both reactants are soluble (no precipitate forms and no simple separation is possible); options B and C are also flawed in their procedures.
✅ Answer: (D)
▶️ Answer/Explanation
The test for ammonium ions (\(\text{NH}_4^+\)) involves adding aqueous sodium hydroxide (\(\text{NaOH}\)) to the salt and warming the mixture.
If ammonium ions are present, ammonia gas (\(\text{NH}_3\)) is produced: \(\text{NH}_4^+ + \text{OH}^- \rightarrow \text{NH}_3 + \text{H}_2\text{O}\); the gas is detected by holding damp red litmus paper near the tube, which turns blue.
✅ Answer: (D)
If ammonium ions are present, ammonia gas (\(\text{NH}_3\)) is produced: \(\text{NH}_4^+ + \text{OH}^- \rightarrow \text{NH}_3 + \text{H}_2\text{O}\); the gas is detected by holding damp red litmus paper near the tube, which turns blue.
✅ Answer: (D)
▶️ Answer/Explanation
Going down Group VII, the halogens become darker in colour: fluorine is pale yellow, chlorine is yellow-green, bromine is orange-brown, and iodine is grey-black (producing a violet vapour).
Therefore, iodine is darker than bromine — statement A is incorrect because it claims bromine is darker than iodine, which is the reverse of the truth.
Statements B, C, and D are all correct facts about the halogens.
✅ Answer: (A)
Therefore, iodine is darker than bromine — statement A is incorrect because it claims bromine is darker than iodine, which is the reverse of the truth.
Statements B, C, and D are all correct facts about the halogens.
✅ Answer: (A)
▶️ Answer/Explanation
Transition elements (e.g. iron, copper, zinc) are characterised by high melting points and high densities due to strong metallic bonding involving d-electrons.
They also form coloured compounds/salts because electrons in their partially filled d-orbitals can absorb specific wavelengths of visible light when transitioning between energy levels.
These three features together — high melting point, high density, coloured salts — are hallmarks of transition metals, matching statement A.
✅ Answer: (A)
They also form coloured compounds/salts because electrons in their partially filled d-orbitals can absorb specific wavelengths of visible light when transitioning between energy levels.
These three features together — high melting point, high density, coloured salts — are hallmarks of transition metals, matching statement A.
✅ Answer: (A)
▶️ Answer/Explanation
Zinc is more reactive than iron and has a greater tendency to form positive ions (statement 1 is correct; statement 3 is incorrect — it reverses the reactivity).
Because zinc is more reactive, even when the zinc coating is scratched, zinc preferentially oxidises instead of iron — this is sacrificial protection (statement 2 is correct).
Statement 4 is incorrect: once scratched, a barrier method fails completely; it is the sacrificial protection that continues to protect the iron through zinc’s preferential corrosion.
✅ Answer: (A)
Because zinc is more reactive, even when the zinc coating is scratched, zinc preferentially oxidises instead of iron — this is sacrificial protection (statement 2 is correct).
Statement 4 is incorrect: once scratched, a barrier method fails completely; it is the sacrificial protection that continues to protect the iron through zinc’s preferential corrosion.
✅ Answer: (A)
▶️ Answer/Explanation
Most fertilisers are formulated to supply the three major plant nutrients: nitrogen (N) for leaf and shoot growth, phosphorus (P) for root development and energy transfer, and potassium (K) for flower/fruit production and disease resistance.
These are collectively known as NPK fertilisers; sodium (Na) and carbon (C) are not primary nutrients in commercial fertilisers.
✅ Answer: (D)
These are collectively known as NPK fertilisers; sodium (Na) and carbon (C) are not primary nutrients in commercial fertilisers.
✅ Answer: (D)
▶️ Answer/Explanation
The Contact process manufactures sulfuric acid through several stages; the key catalysed step is the oxidation of sulfur dioxide to sulfur trioxide: \(2\text{SO}_2 + \text{O}_2 \rightarrow 2\text{SO}_3\).
This reaction is slow without a catalyst, so vanadium(V) oxide (\(\text{V}_2\text{O}_5\)) is used at approximately 450°C to increase the rate while maintaining an acceptable yield.
The other reactions in the process (burning sulfur, absorbing \(\text{SO}_3\), and diluting oleum) do not require this specific catalyst.
✅ Answer: (B)
This reaction is slow without a catalyst, so vanadium(V) oxide (\(\text{V}_2\text{O}_5\)) is used at approximately 450°C to increase the rate while maintaining an acceptable yield.
The other reactions in the process (burning sulfur, absorbing \(\text{SO}_3\), and diluting oleum) do not require this specific catalyst.
✅ Answer: (B)
▶️ Answer/Explanation
A saturated hydrocarbon contains only single C–C bonds (no double bonds), while an unsaturated hydrocarbon contains at least one double bond.
Process 1 (ethene + steam) produces ethanol (\(\text{C}_2\text{H}_5\text{OH}\)), which contains oxygen and is not a hydrocarbon at all, so it does not form a saturated hydrocarbon.
Process 2 (ethene + hydrogen) produces ethane (\(\text{C}_2\text{H}_6\)), a saturated hydrocarbon; process 3 (polymerisation of ethene) produces poly(ethene), which has a saturated carbon backbone (the double bonds open up during polymerisation) — so processes 2 and 3 both form saturated hydrocarbons.
✅ Answer: (D)
Process 1 (ethene + steam) produces ethanol (\(\text{C}_2\text{H}_5\text{OH}\)), which contains oxygen and is not a hydrocarbon at all, so it does not form a saturated hydrocarbon.
Process 2 (ethene + hydrogen) produces ethane (\(\text{C}_2\text{H}_6\)), a saturated hydrocarbon; process 3 (polymerisation of ethene) produces poly(ethene), which has a saturated carbon backbone (the double bonds open up during polymerisation) — so processes 2 and 3 both form saturated hydrocarbons.
✅ Answer: (D)
▶️ Answer/Explanation
Density is defined as \(\rho = \dfrac{m}{V}\); since all four blocks have equal mass, the one with the greatest volume has the lowest density.
The block with the largest dimensions (largest volume) among those of equal mass therefore has the least dense material.
From the diagram, block D has the greatest volume for the same mass, making it the least dense.
✅ Answer: (D)
The block with the largest dimensions (largest volume) among those of equal mass therefore has the least dense material.
From the diagram, block D has the greatest volume for the same mass, making it the least dense.
✅ Answer: (D)
▶️ Answer/Explanation
The pivot is 0.50 m from the rock and \((3.0 – 0.50) = 2.50\) m from where the person pushes.
Applying the principle of moments (clockwise moment = anticlockwise moment): \(F \times 2.50 = 900 \times 0.50\), giving \(F = \dfrac{450}{2.50} = 180 \text{ N}\).
✅ Answer: (B)
Applying the principle of moments (clockwise moment = anticlockwise moment): \(F \times 2.50 = 900 \times 0.50\), giving \(F = \dfrac{450}{2.50} = 180 \text{ N}\).
✅ Answer: (B)
▶️ Answer/Explanation
Coal is a fossil fuel formed from ancient plant material that originally captured energy from sunlight via photosynthesis; hydroelectric power depends on the water cycle driven by solar evaporation; water waves are generated by wind, which is caused by uneven solar heating of the Earth’s surface.
Geothermal energy, however, originates from the decay of radioactive elements within the Earth and from the heat remaining from the planet’s formation — it has no dependence on the Sun.
✅ Answer: (B)
Geothermal energy, however, originates from the decay of radioactive elements within the Earth and from the heat remaining from the planet’s formation — it has no dependence on the Sun.
✅ Answer: (B)
▶️ Answer/Explanation
By Boyle’s Law, at constant temperature, pressure and volume are inversely proportional: \(P \propto \dfrac{1}{V}\), so decreasing the volume increases the pressure.
The explanation is that the same number of gas molecules are now confined to a smaller space, so they collide with the container walls more frequently, exerting a greater force per unit area (greater pressure).
Row D correctly states that pressure increases and gives the correct molecular explanation of more frequent collisions.
✅ Answer: (D)
The explanation is that the same number of gas molecules are now confined to a smaller space, so they collide with the container walls more frequently, exerting a greater force per unit area (greater pressure).
Row D correctly states that pressure increases and gives the correct molecular explanation of more frequent collisions.
✅ Answer: (D)
▶️ Answer/Explanation
Conduction requires physical contact between particles, and convection requires a fluid medium (liquid or gas) — neither can operate through a vacuum.
Radiation involves the emission of electromagnetic waves (including infrared), which can travel through a vacuum at the speed of light and do not require a medium.
Therefore, the only way thermal energy can travel from the Sun through the vacuum of space to Earth is by radiation.
✅ Answer: (C)
Radiation involves the emission of electromagnetic waves (including infrared), which can travel through a vacuum at the speed of light and do not require a medium.
Therefore, the only way thermal energy can travel from the Sun through the vacuum of space to Earth is by radiation.
✅ Answer: (C)
▶️ Answer/Explanation
Glass is optically denser than air, so light slows down as it enters the glass block — this is the cause of refraction.
Since frequency remains unchanged (it is determined by the source), and using the wave equation \(v = f\lambda\), a decrease in wave speed \(v\) at constant frequency \(f\) means the wavelength \(\lambda\) also decreases.
Row A correctly shows both speed and wavelength decrease upon entering the glass.
✅ Answer: (A)
Since frequency remains unchanged (it is determined by the source), and using the wave equation \(v = f\lambda\), a decrease in wave speed \(v\) at constant frequency \(f\) means the wavelength \(\lambda\) also decreases.
Row A correctly shows both speed and wavelength decrease upon entering the glass.
✅ Answer: (A)
▶️ Answer/Explanation
The principal focus of a converging lens is the point on the principal axis where parallel rays of light converge after passing through the lens; it lies between the lens centre and the image for real images.
The focal length is the distance from the optical centre of the lens to the principal focus.
From the diagram, point X is the principal focus (where parallel rays meet) and the distance from the lens centre to X is the focal length — matching row A.
✅ Answer: (A)
The focal length is the distance from the optical centre of the lens to the principal focus.
From the diagram, point X is the principal focus (where parallel rays meet) and the distance from the lens centre to X is the focal length — matching row A.
✅ Answer: (A)
▶️ Answer/Explanation
As current increases through the filament lamp, more electrical energy is dissipated as heat, so the filament’s temperature increases.
Higher temperature causes the metal ions in the filament to vibrate more vigorously, increasing the resistance to electron flow — so resistance also increases.
This is confirmed by the curve’s decreasing gradient (the I–V graph curves, meaning more voltage is needed per unit of current as current rises), consistent with row D: temperature increases, resistance increases.
✅ Answer: (D)
Higher temperature causes the metal ions in the filament to vibrate more vigorously, increasing the resistance to electron flow — so resistance also increases.
This is confirmed by the curve’s decreasing gradient (the I–V graph curves, meaning more voltage is needed per unit of current as current rises), consistent with row D: temperature increases, resistance increases.
✅ Answer: (D)
▶️ Answer/Explanation
For resistors in parallel: \(\dfrac{1}{R_{\text{total}}} = \dfrac{1}{R_1} + \dfrac{1}{R_2} = \dfrac{1}{12} + \dfrac{1}{6} = \dfrac{1}{12} + \dfrac{2}{12} = \dfrac{3}{12} = \dfrac{1}{4}\).
Therefore \(R_{\text{total}} = 4.0\) Ω. Note that the combined resistance in parallel is always less than the smallest individual resistor (6.0 Ω), which confirms 4.0 Ω is correct.
✅ Answer: (B)
Therefore \(R_{\text{total}} = 4.0\) Ω. Note that the combined resistance in parallel is always less than the smallest individual resistor (6.0 Ω), which confirms 4.0 Ω is correct.
✅ Answer: (B)
▶️ Answer/Explanation
The heating of wires is caused by the power dissipated due to the wire’s resistance: \(P = I^2 R\); a thicker wire has a larger cross-sectional area, giving it a lower resistance \(R\).
Lower resistance means less power is dissipated as heat for the same current, so the wires remain cooler.
Using a higher-rated fuse (option B) is dangerous and does not reduce heating; thicker insulation (option D) traps heat rather than reducing it; adding a second fuse in series (option A) would just increase the chance of blowing a fuse but not reduce wire heating.
✅ Answer: (C)
Lower resistance means less power is dissipated as heat for the same current, so the wires remain cooler.
Using a higher-rated fuse (option B) is dangerous and does not reduce heating; thicker insulation (option D) traps heat rather than reducing it; adding a second fuse in series (option A) would just increase the chance of blowing a fuse but not reduce wire heating.
✅ Answer: (C)
▶️ Answer/Explanation
The magnetic field around a straight current-carrying wire forms concentric circles centred on the wire.
Using the right-hand grip rule: if the current goes into the page (represented by a cross ✕), the magnetic field circles the wire in a clockwise direction when viewed from the front.
Diagram A shows concentric circles with a clockwise direction for a current going into the page — this is correct.
✅ Answer: (A)
Using the right-hand grip rule: if the current goes into the page (represented by a cross ✕), the magnetic field circles the wire in a clockwise direction when viewed from the front.
Diagram A shows concentric circles with a clockwise direction for a current going into the page — this is correct.
✅ Answer: (A)
▶️ Answer/Explanation
In an a.c. generator, slip rings rotate with the coil; each end of the coil is permanently connected to one slip ring, and each slip ring remains in contact with the same carbon brush throughout rotation.
This continuous contact allows current to flow to the external circuit without interruption, and because each end of the coil stays connected to the same brush, the output current alternates as the coil rotates — producing a.c.
This contrasts with a split-ring commutator (used in d.c. generators), which swaps connections every half turn to produce direct current.
✅ Answer: (B)
This continuous contact allows current to flow to the external circuit without interruption, and because each end of the coil stays connected to the same brush, the output current alternates as the coil rotates — producing a.c.
This contrasts with a split-ring commutator (used in d.c. generators), which swaps connections every half turn to produce direct current.
✅ Answer: (B)
▶️ Answer/Explanation
Gamma rays are electromagnetic waves with no charge, so they are not deflected by a magnetic field and continue in a straight line.
Beta particles are fast-moving electrons (charge \(-e\)) and are deflected by the magnetic field; the direction of deflection is given by Fleming’s left-hand rule (or the right-hand rule for negative charges), and beta particles deflect in the opposite direction to positive charges (alpha particles).
Row D correctly shows gamma going straight and beta being deflected — confirming the answer.
✅ Answer: (D)
Beta particles are fast-moving electrons (charge \(-e\)) and are deflected by the magnetic field; the direction of deflection is given by Fleming’s left-hand rule (or the right-hand rule for negative charges), and beta particles deflect in the opposite direction to positive charges (alpha particles).
Row D correctly shows gamma going straight and beta being deflected — confirming the answer.
✅ Answer: (D)