RRB ALP CBT 1 2025 PYQs

Concept: These devices work on multiple reflection of sound.

1. They have a tube followed by a conical (flared) opening.
2. Sound waves reflect again and again from the walls of the tube/cone and come out together in the forward direction.
3. So the sound is sent mainly towards the audience without spreading in all directions.

Short trick: "Megaphone = mega-focus": the cone directs sound forward. (Stethoscope and curved hall ceilings also use multiple reflection.)

Answer: (B) Send sound in a specific direction

Concept: Pole (P) is the centre of the mirror surface; principal focus (F) lies on the principal axis.

1. PF = focal length (f).
2. PC = radius of curvature (R) = 2f.
3. Aperture = diameter of the reflecting surface; magnification = image height ÷ object height.

Short trick: "P to F = f; P to C = R = 2f" – F is exactly midway between P and C.

Answer: (A) Focal length

Concept: Movement of food (sugars) made in leaves to other parts is called translocation.

1. It occurs through phloem (sieve tubes, companion cells).
2. It uses energy (ATP) and can move food both upward and downward.
3. Transpiration = loss of water vapour from leaves (xylem pull), not food transport.

Short trick: "Phloem = Food, Xylem = Water" – Food moves by TransLOCATION (food changes LOCATION).

Answer: (D) Translocation

Concept: The sensation of sound persists in our brain for about 0.1 s, so the echo must return after at least 0.1 s.

1. Total path (to the wall and back) $=340\times 0.1=34$ m
2. Minimum distance $=\frac{34}{2}=17$ m

Short trick: Distance $=\frac{v\times 0.1}{2}=\frac{v}{20}$: $\frac{340}{20}=17$ m. (34 m is the round trip – a common trap.)

Answer: (B) 17 m

Concept: In hydrogen, $E_n=-\frac{13.6}{n^2}$ eV, i.e. $E\propto \frac{1}{n^2}$.

1. $\frac{E_4}{E_2}=\frac{2^2}{4^2}=\frac{1}{4}$
2. $E_4=\frac{-3.4}{4}=-0.85$ eV
3. Check: $-\frac{13.6}{16}=-0.85$ eV ✓

Short trick: Doubling n divides energy by 4: −3.4 → −0.85. Energy stays negative and gets closer to 0 in higher orbits.

Answer: (D) −0.85 eV

Concept: The nasal passage and trachea are lined with mucus and hair-like cilia.

1. Mucus traps dust, pollen and germs in the inhaled air.
2. Cilia beat rhythmically and push this mucus up towards the throat, where it is swallowed or coughed out.
3. Gas exchange happens only in the alveoli – not in the upper tract.

Short trick: "Cilia = cleaners / brooms" of the airway; "Alveoli = exchange".

Answer: (D) Removing harmful particles from inhaled air

Concept: Evaporation causes cooling.

1. To change from liquid to vapour, water needs latent heat of vaporisation.
2. It takes this heat from the skin, so the skin temperature falls and we feel cool.
3. Same reason: sweating, earthen pot (matka) cooling, wet cloth on forehead.

Short trick: "Evaporation steals heat" – the escaping molecules carry away energy; condensation does the opposite (releases heat).

Answer: (A) Evaporation of water absorbs heat from the skin surface

Concept: The plasma membrane controls what enters and leaves the cell.

1. It allows some substances (water, O${}_2$, CO${}_2$) to pass freely and regulates others (ions, glucose) using carrier proteins.
2. Because it actively "chooses", it is called selectively permeable.
3. Semi-permeable is a physical term (e.g. an artificial membrane letting only solvent pass); cell wall is fully permeable.

Short trick: "Plasma membrane = Security guard – it SELECTS who enters"; cell wall = open gate (fully permeable).

Answer: (B) selectively permeable

Concept: The Third Schedule contains the forms of oaths or affirmations.

1. It covers Union ministers, candidates for and members of Parliament, Supreme Court judges, CAG, state ministers, MLAs and High Court judges.
2. (The President's and Vice-President's oaths are in Articles 60 and 69, not in this Schedule.)
3. First = States & UTs; Ninth = laws protected from judicial review (1st Amendment); Eleventh = Panchayats (29 subjects).

Short trick: Schedules 1–4 in order: States, Salaries, Oaths, Rajya Sabha seats – "S-S-O-R"; the O (Oath) is 3rd.

Answer: (C) Third Schedule

Concept: Andhra Pradesh announced India's first Quantum Computing Village at its capital Amaravati.

1. It is part of the "Amaravati Quantum Valley" plan, with IBM's quantum computer to be installed there.
2. It supports the National Quantum Mission (2023).

Short trick: "A for Amaravati, A for Andhra – Quantum Valley".

Answer: (C) Andhra Pradesh

Concept: Successive changes multiply: final = $1.10\times 1.20\times 1.15$ of the original.

1. $1.1\times 1.2=1.32$
2. $1.32\times 1.15=1.518$
3. Increase $=51.8\mathrm{\%}$

Short trick: Two-step formula $a+b+\frac{ab}{100}$: 10 and 20 → 32; then 32 and 15 → $32+15+4.8=51.8\mathrm{\%}$.

Answer: (B) 51.8%

Concept: Exposed surfaces = cone curved surface + frustum curved surface + frustum larger base (the joined bases are hidden).

1. Cone slant $l=\sqrt{5^2+{12}^2}=13$ → CSA $=\pi \cdot 5\cdot 13=65\pi$
2. Frustum CSA $=\pi (R+r)l=\pi (22+5)\cdot 32=864\pi$
3. Larger base $=\pi \cdot {22}^2=484\pi$
4. Total $=65\pi +864\pi +484\pi =1413\pi$

Short trick: 5–12–13 triplet gives the slant instantly; unit digit check: 5 + 4 + 4 → ends in 3 → only 1413π.

Answer: (D) $1413\pi$

Concept: Add the three pair-rates: $2(A+B+C)$ is known; subtract a pair to isolate one person.

1. $A+B=\frac{1}{10}$, $B+C=\frac{1}{15}$, $C+A=\frac{1}{20}$
2. Sum $=\frac{6+4+3}{60}=\frac{13}{60}$ → $A+B+C=\frac{13}{120}$
3. $C=\frac{13}{120}-\frac{1}{10}=\frac{1}{120}$ → 120 days

Short trick: Take total work = LCM 60: pair rates 6, 4, 3 → A+B+C = 6.5 → C = 6.5 − 6 = 0.5 per day → 60 ÷ 0.5 = 120 days.

Answer: (A) 120 days

Concept: MN ∥ QR ⇒ $\mathrm{△}PMN\sim \mathrm{△}PQR$; areas are in the ratio of squares of sides.

1. $PM:PQ=4:(4+7)=4:11$
2. $\frac{ar(PMN)}{ar(PQR)}=\frac{16}{121}$ → $ar(PQR)=36\times \frac{121}{16}=272.25$
3. Trapezium $=272.25-36=236.25$

Short trick: Trapezium = small area × $\frac{121-16}{16}=36\times \frac{105}{16}=236.25$ in one step.

Answer: (A) 236.25

Concept: Open brackets from the innermost: ( ) → { } → [ ].

1. $2-4=-2$ → $2-(-2)=4$
2. $3\times 4÷2=6$
3. $[2-6]=-4$
4. $2-(-4)=6$

Short trick: Inside-out with sign care: 4 → 6 → −4 → 6.

Answer: (D) 6

Concept: Work backwards from the last sale using SP = CP × (1 ± r%).

1. Bharath: $CP=\frac{3402}{0.42}=8100$ (this is Anand's SP)
2. Anand: $CP=\frac{8100}{1.25}=6480$
3. This 6480 already includes the ₹175 repair (cost just before selling)

Short trick: $3402\times \frac{100}{42}\times \frac{4}{5}$: 3402 ÷ 42 = 81 → 81 × 80 = 6480.

Answer: (D) 6480

Concept: Compare ratios as decimals (or by how close they are to 1).

1. 8/11 ≈ 0.727, 5/7 ≈ 0.714
2. 13/17 ≈ 0.765, 11/13 ≈ 0.846
3. Greatest: 11 : 13

Short trick: Gap method: 1 − ratio = 3/11, 2/7, 4/17, 2/13; the smallest gap (2/13 ≈ 0.15) is the largest ratio.

Answer: (D) 11 : 13

Concept: Time = distance ÷ speed; downstream $16+s$, upstream $16-s$.

1. $\frac{40}{16+s}+\frac{40}{16-s}=6.4$ h
2. $\frac{40\times 32}{256-s^2}=6.4$ → $256-s^2=200$
3. $s^2=56$ → $s=2\sqrt{14}$ km/h

Short trick: Formula: total time $=\frac{2bD}{b^2-s^2}$ → $b^2-s^2=\frac{2\cdot 16\cdot 40}{6.4}=200$ → $s^2=56$.

Answer: (C) $2\sqrt{14}$

Concept: Subtract the deductions from the total, split in the ratio, then add back.

1. $5890-(320+590+750)=4230$
2. $9+3+6=18$ parts → 1 part $=235$
3. Gita $=3\times 235+590=1295$

Short trick: Ratio 9 : 3 : 6 = 3 : 1 : 2 → Gita gets $\frac{1}{6}$ of 4230 = 705; +590 = 1295.

Answer: (C) ₹1,295

Concept: Overall profit % = weighted average of the individual profit % (weights = share of goods).

1. Shares: 40%, 25% of 60% = 15%, rest = 45%
2. $0.40\times 44=17.6$, $0.15\times 29=4.35$, $0.45\times (-39)=-17.55$
3. $x=17.6+4.35-17.55=4.4$

Short trick: Take 100 items of cost ₹1 each: profit 17.6 + 4.35 − 17.55 = ₹4.4 on ₹100 → 4.4%.

Answer: (A) 4.4%