CTET Science Paper 2 MCQs with Answers Set 01

Answer: (d) Conversion of atmospheric nitrogen to a more usable form for living organisms

Explanation:
1. Nitrogen fixation converts inert atmospheric nitrogen (N₂) into compounds such as ammonia or nitrates.
2. Rhizobium, Azotobacter and lightning do this, so plants can absorb the nitrogen.

Teacher's Note:
1. Option (a) describes denitrification and option (b) describes nitrification.
2. Remember: fixation means taking N₂ from the air into a usable form.

Answer: (a) The spring is neither compressed nor pulled out and is lying on the ground.

Explanation:
1. Elastic potential energy is zero when the spring is in its natural length, neither compressed nor stretched.
2. On the ground there is no gravitational potential energy either, so the total is least in option (a).

Teacher's Note:
1. Both compression and stretching store elastic energy.
2. Height adds gravitational potential energy, so check both kinds.

Answer: (b) kg m²/s², Ws

Explanation:
1. 1 J = 1 N m = 1 kg m²/s², and 1 Ws = 1 W × 1 s = 1 J.
2. So kg m²/s² and Ws are both units of energy (work).
3. kg m/s² is the newton (force) and J/s is the watt (power), so the other pairs differ.

Teacher's Note:
1. Reduce each unit to base units before comparing.
2. Watt-second and kilowatt-hour are units of energy, not power.

Answer: (b) zygote, embryo, uterus, foetus

Explanation:
1. The fused sperm and egg form a zygote (W), which divides to form the developing embryo (X).
2. The embryo implants in the wall of the uterus (Y).
3. When all body parts can be identified, the stage is called the foetus (Z).

Teacher's Note:
1. The order of stages is zygote, embryo, foetus.
2. Fertilisation occurs in the fallopian tube but implantation occurs in the uterus.

Answer: (c) Zn + CaSO₄

Explanation:
1. A metal displaces another from its salt only if it is more reactive than that metal.
2. Fe > Pb, Al > Cu and Mg > Zn, so (a), (b) and (d) occur.
3. Zn is less reactive than Ca, so Zn cannot displace Ca from CaSO₄.

Teacher's Note:
1. Use the reactivity series: K, Na, Ca, Mg, Al, Zn, Fe, Pb, H, Cu, Ag, Au.
2. The metal must be above the one it is replacing.

Answer: (a) A, B and D

Explanation:
1. At rest, distance is constant (horizontal line) and velocity is zero (line along the time axis), so A and D are straight.
2. For uniform acceleration v = u + at, a straight line, so B is straight.
3. Distance s = ut + ½at² is a parabola, so C is curved.

Teacher's Note:
1. Uniform acceleration gives a straight v-t graph but a curved s-t graph.
2. A line along the time axis still counts as a straight line.

Answer: (c) (A) is false, but (R) is true.

Explanation:
1. Current has magnitude and a direction of flow, so R is true as a statement.
2. But it does not obey the vector addition law (triangle law), so it is a scalar and A is false.

Teacher's Note:
1. Having direction is not enough to make a quantity a vector; it must add by the vector rules.
2. Current, pressure and surface-tension are other direction-like scalars.

Answer: (c) A, B and C

Explanation:
1. The nucleus holds the main DNA of the cell.
2. Mitochondria and plastids have their own circular DNA and ribosomes.
3. Vacuoles contain no DNA.

Teacher's Note:
1. Mitochondria and plastids are semi-autonomous organelles.
2. This supports the endosymbiotic origin of these organelles.

Answer: (b) a-v, b-iv, c-i, d-ii, e-iii

Explanation:
1. Plastic takes several years (v); silk takes about 4 years (iv); cotton takes 2-5 months (i).
2. Banana peel takes 1-2 weeks (ii) and paper takes 10-30 days (iii).
3. This matches a-v, b-iv, c-i, d-ii, e-iii.

Teacher's Note:
1. Plastic is non-biodegradable and lasts the longest.
2. Natural fibres and food waste decompose faster.

Answer: (a) Zero

Explanation:
1. Constant velocity means zero acceleration.
2. By Newton's second law, net force = mass × acceleration = 0.
3. Air resistance exactly balances the weight.

Teacher's Note:
1. Do not multiply mass by g here; weight is not the net force once drag balances it.
2. Falling at constant (terminal) velocity means balanced forces.

Answer: (d) 13, 10 and 14

Explanation:
1. Protons = atomic number = 13.
2. The 3+ ion has lost 3 electrons, so electrons = 13 − 3 = 10.
3. Neutrons = 27 − 13 = 14.

Teacher's Note:
1. Ionisation changes electrons only, never protons or neutrons.
2. Neutrons = mass number − atomic number.

Answer: (b) A & B

Explanation:
1. HCl in water gives H⁺ and Cl⁻ ions, and caustic soda (NaOH) gives Na⁺ and OH⁻ ions, so A and B conduct.
2. Sugar dissolves as molecules and gives no ions, so C does not conduct.

Teacher's Note:
1. Distilled water alone does not conduct.
2. Acids, bases and salts conduct in solution; sugar and alcohol do not.

Answer: (c) S₁ is incorrect and S₂ is correct

Explanation:
1. The moon has gravity about one sixth of the earth's, so S₁ is incorrect.
2. The moon has no atmosphere and so no oxygen, so S₂ is correct.

Teacher's Note:
1. Weak gravity is not zero gravity.
2. The moon's low gravity is why it cannot hold an atmosphere.

Answer: (b) Only (B)

Explanation:
1. Aquatic plants are surrounded by water, which they absorb over the whole body surface.
2. So they do not need long roots; they still absorb minerals, and roots do not decide floating.

Teacher's Note:
1. Roots in such plants mainly act as anchors or are reduced.
2. Avoid statements that suggest a plant is built for human convenience.

Answer: (b) A straight line parallel to the time-axis

Explanation:
1. The slope of a velocity-time graph equals acceleration.
2. Zero acceleration means zero slope, a straight line parallel to the time axis.

Teacher's Note:
1. A line parallel to the velocity axis is not possible for a moving body.
2. A constant finite slope means uniform acceleration.

Answer: (d) Both Raman & Shiksha are 5 m from the mirror

Explanation:
1. In a plane mirror the image is as far behind as the object is in front, so Raman's distance = 10 ÷ 2 = 5 m.
2. Shiksha is now 11 − 6 = 5 m from the mirror.

Teacher's Note:
1. Object-to-image distance is twice the object distance.
2. A common mistake is to take 10 m as the distance from the mirror.

Answer: (b) Carbon monoxide

Explanation:
1. Incomplete combustion with limited oxygen forms carbon monoxide (CO).
2. CO binds haemoglobin more strongly than oxygen, lowering oxygen transport.

Teacher's Note:
1. Complete combustion gives CO₂.
2. Never use a coal or charcoal heater in a closed room.

Answer: (b) Static friction > Sliding friction > Rolling friction

Explanation:
1. Static friction (limiting) is greater than sliding (kinetic) friction.
2. Rolling friction is the smallest of the three.

Teacher's Note:
1. It takes more force to start an object moving than to keep it moving.
2. This is why wheels and ball bearings reduce friction.

Answer: (a) Manually uproot the weeds

Explanation:
1. Uprooting weeds by hand removes the whole plant without chemicals.
2. Weedicides can harm crops, soil and farmers, and burning stubble pollutes the air.

Teacher's Note:
1. Removing only flowers and seeds leaves the weed alive.
2. Weeding should be done before the weeds flower and set seed.

Answer: (d) The activity should lead to conceptual understanding

Explanation:
1. The purpose of any science activity is to build understanding of concepts.
2. Fun, hands-on work and variety are useful, but only if they lead to conceptual understanding.

Teacher's Note:
1. An activity that is merely fun may not teach the concept.
2. Always ask what the learner will understand at the end.

Answer: (c) Amplitude of vibration of roar of lion is larger as compared to bird's sound.

Explanation:
1. Loudness depends on the amplitude of vibration.
2. A lion's roar has a larger amplitude, so it is louder.

Teacher's Note:
1. Pitch (shrillness) depends on frequency, not loudness.
2. A bird's sound has a higher frequency, but a smaller amplitude.

Answer: (a) Vitamin D

Explanation:
1. Vitamin D helps the intestine absorb calcium.
2. Its deficiency causes poor calcium absorption, leading to rickets in children.

Teacher's Note:
1. Sunlight helps the skin make vitamin D.
2. Vitamin C deficiency gives scurvy and vitamin K deficiency affects blood clotting.

Answer: (d) Freely suspending the magnet from the middle.

Explanation:
1. A freely suspended magnet comes to rest along the north-south direction.
2. The end pointing north is the north pole.

Teacher's Note:
1. Iron is attracted by both poles, so it cannot tell them apart.
2. Bringing it near another magnet needs a magnet with known poles.

Answer: (d) B and D

Explanation:
1. Inquiry involves investigating a question by testing, comparing or exploring.
2. B (comparing melting rates) and D (exploring factors for floating) are investigations.
3. A and C only need identification or recall.

Teacher's Note:
1. Look for tasks that need the learner to question, plan and test.
2. Listing and identifying tasks assess recall, not inquiry.

Answer: (a) communicating

Explanation:
1. Representing data in a graph is a way of presenting information to others.
2. This is the process skill of communicating.

Teacher's Note:
1. Reading meaning from the graph afterwards would be interpreting.
2. Communicating includes tables, graphs, drawings and reports.

Answer: (c) (A) & (D)

Explanation:
1. Hibiscus is a dicot with reticulate venation and a tap root, so (A) is incorrect.
2. Paddy is a monocot with parallel venation and a fibrous root, so (D) is incorrect.
3. (B) and (C) are correct.

Teacher's Note:
1. Dicots have reticulate venation and tap roots; monocots have parallel venation and fibrous roots.
2. Bamboo and paddy are grasses, hence monocots.

Answer: (a) They all lack back bone

Explanation:
1. Amoeba is a protozoan, starfish is an echinoderm, and ant and spider are arthropods.
2. None of them has a backbone, so all are invertebrates.

Teacher's Note:
1. Amoeba reproduces by binary fission, so 'lay eggs' fails.
2. Ant and spider live on land, so 'live in water' fails.

Answer: (c) Heat the leaf on a flame

Explanation:
1. The leaf is boiled in water, then in alcohol to remove chlorophyll, washed, and tested with iodine.
2. Heating the leaf directly on a flame is not a step, and alcohol is never heated directly.

Teacher's Note:
1. Alcohol is flammable, so it is heated in a water bath.
2. A blue-black colour with iodine shows starch.

Answer: (c) By flooding lands with saline water

Explanation:
1. Cyclones push sea water onto the coast and flood the land.
2. The salt left behind makes the soil saline and less fertile.

Teacher's Note:
1. Salinity harms plant roots by drawing water out of them.
2. Sea-water flooding is also called storm surge.

Answer: (c) (A) and (B)

Explanation:
1. A rocket fuel must be light and have a high calorific value to give large thrust.
2. It burns rapidly, not slowly, so (C) is incorrect.

Teacher's Note:
1. Rockets carry their own oxidiser, so they can burn in space.
2. Liquid hydrogen is a common rocket fuel.