RRB Technician Grade III 2024, 2025 PYQs

Concept: Work done by a constant force: $W=F\times s\times \cos \theta$.

1. Displacement is in the direction of the force, so $\theta =0^{\circ }$ and $\cos 0^{\circ }=1$.
2. $W=10\times D\times 1=10D\text{J}$
3. Force and displacement are in the same direction, so work is positive.

Yaad rakhein: $\theta ={90}^{\circ }$ → zero work; $\theta ={180}^{\circ }$ → negative work.

Answer: (C) $+10\text{D}$

Concept: A freely falling body moves only under gravity, so its acceleration is constant: $g\approx 9.8{\text{m s}}^{-2}$ (air resistance neglected).

1. Velocity increases by the same amount every second ($v=u+gt$).
2. Equal change in velocity in equal time intervals = uniform acceleration.
3. Speed and velocity keep changing, so options (C) and (D) are wrong; acceleration is not changing, so (B) is wrong.

Yaad rakhein: Free fall = constant $g$ = uniformly accelerated motion.

Answer: (A) uniformly accelerated motion

Concept: NaCl is formed by transfer of one electron from sodium to chlorine.

1. Na (2, 8, 1) loses 1 electron → $\mathrm{N}{\mathrm{a}}^{+}$ (cation, positive).
2. Cl (2, 8, 7) gains 1 electron → $\mathrm{C}{\mathrm{l}}^{-}$ (anion, negative).
3. Opposite charges attract strongly → ionic bond in $\mathrm{N}{\mathrm{a}}^{+}\mathrm{C}{\mathrm{l}}^{-}$.

Yaad rakhein: Metals lose electrons → positive ions; non-metals gain electrons → negative ions.

Answer: (A) Na ions are positively charged, and Cl ions are negatively charged.

Concept: Pressure brings particles closer; lowering temperature reduces their kinetic energy. Both help change gas → liquid/solid.

1. Statement I: gases (e.g. LPG) are liquefied by high pressure and low temperature – correct.
2. Statement II: solid $\mathrm{C}{\mathrm{O}}_2$ (dry ice) is stored under high pressure; when pressure drops to 1 atm it sublimes directly to gas – correct.
3. So both statements are correct.

Yaad rakhein: Dry ice = solid $\mathrm{C}{\mathrm{O}}_2$; at 1 atm it changes directly into gas (sublimation).

Answer: (D) Both statements I and II are correct.

Concept: Pressure is force acting per unit area: $P=\frac{F}{A}$.

1. SI unit = $\frac{\text{N}}{{\text{m}}^2}$, named pascal (Pa).
2. Newton is the unit of force; Newton/metre is the unit of surface tension or spring constant.
3. Angstrom (${10}^{-10}\text{m}$) is a unit of length.

Yaad rakhein: $1\text{Pa}=1{\text{N m}}^{-2}$ (area in the denominator, not length).

Answer: (D) Pascal

Concept: In the first step of respiration (glycolysis, in the cytoplasm), glucose is broken into pyruvate.

1. Glucose = ${\mathrm{C}}_6{\mathrm{H}}_{12}{\mathrm{O}}_6$, a six-carbon molecule.
2. One glucose splits into two molecules of pyruvate.
3. So each pyruvate has $\frac{6}{2}=3$ carbon atoms.

Trick: Glucose (6C) ÷ 2 = pyruvate (3C) – think 'half'.

Answer: (D) three-carbon molecule

Concept: Magnification $m=\frac{h^{\prime }}{h}$. A concave lens always forms a virtual, erect, diminished image, so $m$ is positive and less than 1.

1. Object height $h=30\text{cm}$, image height $h^{\prime }=10\text{cm}$ (erect, so positive).
2. $m=\frac{10}{30}=\frac{1}{3}$.
3. Positive and $<1$ – matches a concave lens.

Trick: Concave lens: $0<m<1$ always – pick the positive fraction.

Answer: (A) $1/3$

Concept: Magnetic field lines are closed continuous curves.

1. Outside the magnet they emerge from the North pole and enter the South pole.
2. To complete the closed loop, inside the magnet they go from the South pole to the North pole.
3. They never intersect and are not 'perpendicular to a pole'.

Yaad rakhein: Outside N → S, inside S → N: a closed loop.

Answer: (A) South pole to its North pole

Concept: Each part of the female reproductive system has a specific role in pregnancy.

1. Placenta: disc-like tissue that passes nutrition (and oxygen) from mother's blood to the embryo → A-i.
2. Fallopian tube (oviduct): site where sperm meets egg → fertilization → B-ii.
3. Uterus: the embryo gets embedded (implanted) in its thick lining → C-iii.

Yaad rakhein: Tube = fertilization, Uterus = implantation, Placenta = nutrition.

Answer: (D) A-i, B-ii, C-iii

Concept: Muscles that move according to our will are called voluntary (striated/skeletal) muscles.

1. Limb muscles (arms, legs) contract and relax when we decide – voluntary.
2. Involuntary (unstriated/smooth) muscles, e.g. in the stomach and intestine, work on their own.
3. Cardiac muscles of the heart are also involuntary and work rhythmically all life.

Yaad rakhein: Will = voluntary = striated (limbs); heart and gut = involuntary.

Answer: (A) voluntary muscles

Concept: In a gas, particles are far apart and move fast. To liquefy it, particles must be brought close and slowed down.

1. High pressure compresses the gas → particles come closer.
2. Low temperature reduces kinetic energy → attraction can hold particles together.
3. Hence high pressure + low temperature liquefies a gas (e.g. LPG, liquid ${\mathrm{N}}_2$).

Trick: 'HP–LT': High Pressure, Low Temperature → liquid.

Answer: (C) high pressure and low temperature

Concept: For a concave mirror, the image position depends on where the object is placed relative to F and C (radius $R=2f$).

1. Object beyond C → image between F and C, diminished.
2. Object at C → image also at C, real, inverted and of the same size.
3. Object between F and C → image beyond C, enlarged; object at F → image at infinity.

Yaad rakhein: Same size real image only when object is at C ($u=-2f\Rightarrow v=-2f$, $m=-1$).

Answer: (B) at the centre of curvature

Concept: Inertia is the tendency of a body to resist a change in its state of rest or uniform motion. Mass is the measure of inertia.

1. A heavier body (more mass) is harder to start, stop or turn.
2. Pushing a loaded truck vs. an empty cart shows greater mass → greater inertia.
3. So inertia increases directly with mass: inertia $\propto$ mass.

Yaad rakhein: Mass = measure of inertia; more mass, more inertia.

Answer: (C) Inertia is proportional to mass.

Concept: Evaporation takes latent heat from the surface, producing cooling.

1. In summer we sweat more.
2. Cotton absorbs sweat and exposes it to the air, so it evaporates quickly.
3. The evaporating sweat takes heat from the body → body feels cool.

Yaad rakhein: Sweat + cotton + evaporation = cooling (same reason earthen pots keep water cool).

Answer: (C) Evaporation

Concept: Ionic compounds are formed by transfer of electrons between a metal and a non-metal.

1. Table salt $\mathrm{N}\mathrm{a}\mathrm{C}\mathrm{l}$ = $\mathrm{N}{\mathrm{a}}^{+}$ and $\mathrm{C}{\mathrm{l}}^{-}$ ions → ionic.
2. Glucose (${\mathrm{C}}_6{\mathrm{H}}_{12}{\mathrm{O}}_6$) and sugar (sucrose) are covalent compounds of C, H, O.
3. Turmeric is a natural mixture (mainly the organic compound curcumin), not ionic.

Trick: Metal + non-metal → usually ionic; only non-metals (C, H, O) → covalent.

Answer: (C) Table salt

Concept: From $F=\frac{G{m}_1{m}_2}{r^2}$, $G=\frac{F{r}^2}{m_1{m}_2}$, so its unit is ${\text{N m}}^2{\text{kg}}^{-2}$.

1. $G=6.7\times {10}^{-11}{\text{N m}}^2{\text{kg}}^{-2}$ – option (C).
2. $9.1\times {10}^{-31}\text{kg}$ = mass of an electron; $1.6\times {10}^{-19}\text{C}$ = charge of an electron.
3. $9.8{\text{m s}}^{-2}$ = $g$, acceleration due to gravity (not $G$).

Trick: Match by unit: only $G$ has ${\text{N m}}^2{\text{kg}}^{-2}$.

Answer: (C) $6.7\times {10}^{-11}N{m}^{2}k{g}^{-2}$

Concept: pH scale (0 to 14) measures the hydrogen-ion concentration, i.e. how acidic or basic a solution is.

1. pH $<7$ → acidic; pH $=7$ → neutral; pH $>7$ → basic.
2. Lower pH = stronger acid; higher pH = stronger base.
3. It does not measure pollution, density or volume.

Yaad rakhein: 'p' = potenz (power) of ${\mathrm{H}}^{+}$; 7 is neutral.

Answer: (B) acidity or basicity

Concept: In a mixture components keep their own properties; in a compound elements combine chemically in a fixed ratio to form a new substance.

1. Mixture (e.g. iron filings + sulphur powder): no new substance → physical change.
2. Compound (heating Fe + S → $\mathrm{F}\mathrm{e}\mathrm{S}$): new substance with new properties → chemical change.
3. So the answer is physical, chemical.

Yaad rakhein: Mixture = separable by physical methods; compound = new substance, needs chemical methods.

Answer: (B) physical, chemical

Concept: The pituitary gland (at the base of the brain) secretes growth hormone, which regulates growth and development of the body.

1. Deficiency in childhood → dwarfism; excess → gigantism.
2. Adrenal → adrenaline; pancreas → insulin; thyroid → thyroxin.
3. So growth hormone comes from the pituitary.

Yaad rakhein: Pituitary = 'master gland' and source of growth hormone.

Answer: (B) Pituitary

Concept: For a freely falling body, total mechanical energy (PE + KE) remains constant; PE changes into KE as it falls.

1. At the top: all potential energy $mgh$, KE $=0$.
2. At the midpoint: height $\frac{h}{2}$, so PE $=\frac{mgh}{2}$ and KE $=\frac{mgh}{2}$.
3. Just before the ground: almost all KE. So at the midpoint it has both PE and KE.

Yaad rakhein: Midway in free fall: PE = KE = half of total energy.

Answer: (D) Both Potential and Kinetic