RRB Technician Grade III 2024, 2025 PYQs

Concept: W = F × s; work is zero if displacement is zero.

Solution:

1. Standing still → load does not move → s = 0.
2. W = F × 0 = 0, even though muscles use energy (we feel tired).

Yaad rakhein: Work is also zero when force ⟂ displacement (e.g. carrying a load horizontally).

Answer: (C) There is no displacement of the load.

Concept: Cilia beat rhythmically to move substances.

Solution:

1. In the respiratory tract, cilia push mucus (with trapped dust and germs) upward to be cleared.
2. Secretion is done by goblet/gland cells, not cilia.

Yaad rakhein: Ciliated columnar epithelium is also found in fallopian tubes (moves the ovum).

Answer: (A) To move and push mucus forward to clear it

Concept: Balanced use of manures and fertilisers keeps soil healthy and raises yield.

Solution:

1. Supplies macro- and micronutrients in the right amount.
2. Maintains soil fertility and gives optimum crop yield; other options are harmful or irrelevant.

Yaad rakhein: Manures add organic matter; fertilisers give quick nutrients — integrated use is best.

Answer: (B) To optimize soil fertility and crop yield

Concept: Golgi = cell's packaging and dispatch centre.

Solution:

1. Modifies, packages and secretes materials made in the ER.
2. Also forms lysosomes.
3. Protein synthesis → ribosomes; ATP → mitochondria; photosynthesis → chloroplasts.

Yaad rakhein: Golgi apparatus was first described by Camillo Golgi.

Answer: (D) Packaging and secretion of materials

Concept: Food moves through sieve tubes of phloem.

Solution:

1. Sieve tubes have sieve plates through which food (sucrose) flows.
2. Companion cells support sieve tubes; fibres give strength.

Yaad rakhein: Phloem elements: sieve tubes, companion cells, phloem parenchyma, phloem fibres (only fibres are dead).

Answer: (C) Sieve tubes

Concept: Speed of sound depends on the medium's nature and temperature.

Solution:

1. Speed increases with temperature (e.g. ~331 m/s at 0 °C, ~344 m/s at 22 °C in air).
2. At constant temperature, pressure has no effect; amplitude does not change speed.

Yaad rakhein: Speed: solids > liquids > gases.

Answer: (C) Temperature

Concept: Rhizopus reproduces by spore formation.

Solution:

1. Thread-like hyphae bear erect stalks.
2. The tiny blobs on top are sporangia, which contain spores.

Yaad rakhein: Sporangium is the case; spores are inside it — don't confuse the two.

Answer: (D) Sporangia

Concept: Soap molecules have a hydrophilic ionic head and a hydrophobic hydrocarbon tail.

Solution:

1. In water, tails turn inward (away from water) and heads face outward.
2. This forms a micelle that traps oil/dirt in its centre.

Yaad rakhein: Soap does not work well in hard water — it forms scum with Ca²⁺/Mg²⁺.

Answer: (A) hydrophobic and hydrophilic interactions in water

Concept: Lens formula: $\frac{1}{v}-\frac{1}{u}=\frac{1}{f}$.

Solution:

1. Applies to both convex and concave lenses with sign convention.
2. Mirror formula differs: $\frac{1}{v}+\frac{1}{u}=\frac{1}{f}$.

Trick: Lens has minus, mirror has plus — 'L for Less (minus)'.

Answer: (A) (1/v) - (1/u) = 1/f

Concept: Solid sol = solid dispersed in a solid medium.

Solution:

1. Coloured gemstone, milky glass: solid in solid ✓.
2. Jelly, cheese = gel (liquid in solid); smoke = aerosol (solid in gas).

Yaad rakhein: Sol = solid in liquid (paint); aerosol = in gas (fog, smoke); emulsion = liquid in liquid (milk).

Answer: (A) Coloured gem

Concept: Decomposers break down dead matter and return nutrients to soil.

Solution:

1. Without them, dead bodies and waste would pile up.
2. Nutrients would stay locked → nutrient cycling stops.
3. Plant growth would fall, not rise, due to lack of recycled nutrients.

Yaad rakhein: Bacteria and fungi are the main decomposers.

Answer: (D) Accumulation of waste and dead matter, disrupting nutrient cycling

Concept: $F=ma$, with $a=\frac{v-u}{t}$.

Solution:

1. $a=\frac{10-0}{2}=5$ m/s².
2. $F=50\times 5=250$ N.

Trick: $F=\frac{m(v-u)}{t}=\frac{50\times 10}{2}=250$ N (rate of change of momentum).

Answer: (D) 250 N

Concept: BP is written as systolic/diastolic.

Solution:

1. Systolic: pressure when ventricles contract (~120 mm Hg).
2. Diastolic: pressure when ventricles relax (~80 mm Hg).

Trick: S for Squeeze (contract), D for Dilate/relax.

Answer: (A) Systolic; Diastolic

Concept: Pregnancy is established only after the blastocyst implants in the uterine wall.

Solution:

1. A ✓: if implantation fails, the embryo cannot stay and is lost.
2. R ✓: implantation = embedding of blastocyst in endometrium.
3. R directly explains why failed implantation means no pregnancy.

Yaad rakhein: After implantation, the placenta forms to nourish the embryo.

Answer: (D) Both A and R are true, and R is the correct explanation of A

Concept: Proper crop production management raises yield.

Solution:

1. Timely irrigation and fertilisation meet water and nutrient needs at critical stages.
2. Monocropping, delayed harvest and ignoring pests reduce yield.

Yaad rakhein: Three pillars: crop variety improvement, crop production management, crop protection.

Answer: (C) Timely irrigation and fertilization

Concept: Connective tissue cells lie in an extracellular matrix.

Solution:

1. The matrix (with fibres) binds and supports organs.
2. Contractile proteins = muscle; nerve endings = nervous; cilia = epithelium.

Yaad rakhein: Blood's matrix is plasma; bone's matrix is hard due to calcium and phosphorus.

Answer: (C) Presence of extracellular matrix

Concept: $\frac{1}{v}-\frac{1}{u}=\frac{1}{f}$; for concave lens f and v are negative.

Solution:

1. f = −15 cm, v = −10 cm (virtual image, same side).
2. $\frac{1}{u}=\frac{1}{v}-\frac{1}{f}=-\frac{1}{10}+\frac{1}{15}=-\frac{1}{30}$.
3. $u=-30$ cm.

Trick: $u=\frac{fv}{f-v}=\frac{(-15)(-10)}{-15+10}=\frac{150}{-5}=-30$.

Answer: (B) -30 cm

Concept: Concentration methods exploit differences between ore and gangue.

Solution:

1. Hydraulic washing → density difference.
2. Froth flotation → wetting by oil vs water (sulphide ores).
3. Magnetic separation → magnetic vs non-magnetic.

Yaad rakhein: Froth flotation is used for sulphide ores like ZnS (zinc blende).

Answer: (C) Because each method exploits specific differences in physical and chemical properties between the ore and the gangue

Concept: Molecular mass = sum of atomic masses.

Solution:

1. N₂ = $2\times 14=28$ u; O₂ = $2\times 16=32$ u.
2. 28 : 32 = 7 : 8.

Trick: Ratio of molecules = ratio of atoms here: 14 : 16 = 7 : 8.

Answer: (B) 7 : 8

Concept: Olfactory indicators change smell in acidic/basic medium.

Solution:

1. Onion, vanilla and clove oil lose their smell in bases.
2. Since detection is by smell, not colour, they help visually impaired people.

Yaad rakhein: Vanilla and onion smell is lost in base, but stays in acid.

Answer: (D) They are useful for visually impaired individuals.