Q&A: practice questions with answers

Concept: Look for the pattern Even–Even–Odd, where the middle even digit is counted.

1. Scan for two consecutive even digits followed by an odd digit.
2. “4 6 7”: 6 is preceded by 4 (even) and followed by 7 (odd) ✓.
3. “2 8 3”: 8 is preceded by 2 (even) and followed by 3 (odd) ✓.
4. No other place fits, so the count is 2.

Trick: First locate the even digits that are followed by an odd one, then check their left neighbour.

Answer: (C) 2

Concept: Use alphabet positions and find the rule between the pairs.

1. LH-KG-JI: L(12)→K(11)→J(10) is $-1$ each; H(8)→G(7) is $-1$, G(7)→I(9) is $+2$.
2. VR-UQ-TS follows the same: $-1,-1$ and $-1,+2$.
3. TP-SO-RQ: T→S→R is $-1$; P(16)→O(15) is $-1$, O(15)→Q(17) is $+2$ ✓.

Trick: First letters fall by 1; second letters go $-1$ then $+2$.

Answer: (B) TP-SO-RQ

Concept: Find the differences between consecutive terms.

1. $534-429=+105$, $452-534=-82$.
2. $557-452=+105$, $475-557=-82$.
3. Next: $475+105=580$.

Trick: Alternating pattern $+105,-82$ repeats.

Answer: (C) 580

Concept: Plot each move; a left turn while facing South points East, and so on.

1. A → 6 km South.
2. Left (now East) 4 km; left again (now North) 6 km — back on A’s level, 4 km East of A.
3. Right (now East) 4 km to B, so B is 8 km East of A.
4. To return, drive 8 km West.

Trick: The two 6 km legs (South and North) cancel; only East moves remain: $4+4=8$ km.

Answer: (D) 8 km West

Concept: Two negative statements give no definite conclusion between the end terms.

1. Statue and Copy are both separate from Book, but their mutual relation is unknown — I does not follow.
2. “No statue is a book” directly contradicts “Some books are statues” — II does not follow.

Yaad rakhein: Two negative premises → no definite conclusion.

Answer: (A) Neither conclusion (I) nor (II) follows

Concept: Common words in two sentences share the common codes.

1. Common words: “wind”, “dances”; common codes: snxk, vzod.
2. In sentence 2, the remaining word “gracefully” gets the remaining code.
3. gracefully = lwon.

Trick: Remove the shared codes; the unique word takes the unique code.

Answer: (B) lwon

Concept: An effect is a reaction or result that follows from a cause.

1. Statement I: sugar is found to be the main reason for diabetes — a finding (cause).
2. Statement II: people avoiding sugary foods is a reaction to that finding (effect).

Trick: Ask “which statement explains why the other happened?” — that one is the cause.

Answer: (A) I is the cause and II is its possible effect

Concept: Number the seats 1 to 7 from left to right (all face North).

1. Two people left of A → A is at 3.
2. Three between A and Y → Y at 7; L second to the right of A → L at 5.
3. Two between L and Z → Z at 2.
4. Seats 1, 4, 6 remain with B left of C left of X → B = 1, C = 4, X = 6. Right of C: L, X, Y = 3.

Trick: Place the definite clues (A, Y, L) first; the “between” clue then fixes the rest.

Answer: (C) Three

Concept: Test the options to find one rule that fits both pairs.

1. Try $X=13$: $13\times 9-1=117-1=116$ ✓.
2. Apply the same rule to 16: $16\times 9-1=144-1=143$.
3. So $X=13$, $Y=143$.

Trick: Rule: multiply by 9, then subtract 1. Options with 145 or 144 break the rule.

Answer: (C) X = 13, Y = 143

Concept: Track each letter position separately.

1. 1st letters: D, G, J, M, P (each $+3$).
2. 2nd letters: Z, Y, X, W, V (each $-1$).
3. 3rd letters: M, L, K, J, I (each $-1$).

Trick: Only the first letter jumps by 3; the other two step back by 1.

Answer: (D) PVI

Concept: The male reproductive system includes testes (inside the scrotum), vas deferens, urethra, penis and accessory glands (seminal vesicles, prostate).

1. Uterus, vagina, fallopian tube (oviduct) belong to the female system.
2. Options (A), (B), (D) each contain a female organ.
3. Vas deferens carries sperms from testis; scrotum holds the testes outside the body for lower temperature.

Yaad rakhein: Oviduct = fallopian tube = female; vas deferens = sperm duct = male.

Answer: (C) Vas deferens and scrotum

Concept: Newton's law: $F=\frac{G{m}_1{m}_2}{d^2}$. Force is directly proportional to the product of masses and inversely proportional to the square of the distance.

1. Doubling one mass doubles $F$.
2. Doubling distance makes $F$ one-fourth, i.e. $\frac{F}{4}$.
3. So the force depends on both masses and distance.

Yaad rakhein: Inverse square law: $F\propto \frac{1}{d^2}$; $G=6.67\times {10}^{-11}{\text{N m}}^2{\text{kg}}^{-2}$.

Answer: (B) depends on the masses of the objects and the distance between them

Concept: Evaporation is the change of liquid into vapour at any temperature below the boiling point, taking place at the surface.

1. Higher temperature, larger surface area and higher wind speed all increase evaporation.
2. Humidity means air already holds a lot of water vapour.
3. Such air cannot take in more vapour, so the rate of evaporation decreases.

Trick: Wet clothes dry slowly on a humid (rainy) day – humidity is the only 'decreasing' factor here.

Answer: (D) Increase in humidity

Concept: Second law: the rate of change of momentum of a body is directly proportional to the applied unbalanced force, in the direction of the force: $F\propto \frac{\Delta p}{t}$.

1. Momentum $p=mv$.
2. $F=\frac{m(v-u)}{t}=ma$.
3. Torque relates to rate of change of angular momentum, not linear momentum.

Yaad rakhein: Second law gives $F=ma$; unit $1\text{N}=1{\text{kg m s}}^{-2}$.

Answer: (A) force

Concept: First law: a body stays at rest or in uniform straight-line motion unless an unbalanced external force acts on it.

1. The tendency of a body to resist a change in its state is called inertia.
2. Because the first law describes this property, it is called the law of inertia.
3. Mass is the measure of inertia.

Trick: 1st law → inertia, 2nd law → F = ma (momentum), 3rd law → action–reaction.

Answer: (B) law of inertia

Concept: Variation means differences among individuals of a species, arising mainly during sexual reproduction and DNA copying.

1. Environments change (heat, drought, disease).
2. If all individuals were identical, one change could wipe out the whole population.
3. Individuals with useful variations survive and pass them on – so variation ensures long-term survival of the species.

Yaad rakhein: Variation is the raw material for evolution and natural selection.

Answer: (C) Variation

Concept: A decomposition reaction in which a single compound breaks down on heating is called thermal decomposition.

1. Heating limestone: $\mathrm{C}\mathrm{a}\mathrm{C}{\mathrm{O}}_3(\mathrm{s})\stackrel{\text{heat}}{\to }\mathrm{C}\mathrm{a}\mathrm{O}(\mathrm{s})+\mathrm{C}{\mathrm{O}}_2(\mathrm{g})$.
2. One reactant gives two products → decomposition.
3. Energy supplied as heat → thermal decomposition (it is endothermic, not exothermic).

Yaad rakhein: Heat → thermal, light → photolytic, electricity → electrolytic decomposition.

Answer: (B) thermal decomposition

Concept: Plastids are large membrane-bound organelles found only in plant cells; chloroplasts (green plastids) contain chlorophyll and carry out photosynthesis.

1. Nucleus controls cell activities.
2. Golgi body packages and transports materials.
3. Lysosomes digest waste (suicide bags).
4. Only plastids (chloroplasts) trap sunlight for photosynthesis.

Yaad rakhein: Chloroplasts and mitochondria both have their own DNA and ribosomes.

Answer: (D) Plastids

Concept: Power of a lens $P=\frac{1}{f}$ ($f$ in metre), unit dioptre (D). So power is inversely related to focal length.

1. $f=0.5\text{m}\Rightarrow P=2\text{D}$; $f=2\text{m}\Rightarrow P=0.5\text{D}$.
2. Larger focal length → smaller power, so statement (B) is wrong.
3. Convex lens: f positive → P positive; concave lens: P negative.

Trick: Short focal length = strong (powerful) lens.

Answer: (B) Larger the focal length, larger the power.

Concept: Enzymes are biological catalysts that break down complex food into simple, absorbable substances.

1. (i) Food is digested by enzymes like amylase, pepsin, trypsin, lipase – correct.
2. (ii) Each enzyme acts on a particular substrate (lock-and-key) – correct.
3. (iii) Hence a specific enzyme is needed for a specific substance, e.g. cellulose needs cellulase, which humans lack – correct.

Yaad rakhein: Amylase → starch, pepsin/trypsin → proteins, lipase → fats.

Answer: (D) (i), (ii) and (iii)