RRB Technician Grade III 2024, 2025 PYQs

Concept: Yield rises with good inputs and protection together.

1. Quality seeds, timely irrigation, fertilisers and crop protection all raise yield.
2. Other options (poor seeds, rain only, no protection) reduce yield.

Yaad rakhein: Three stages of crop improvement: choice of seeds, nurturing of crops, protection of crops.

Answer: (D) Using quality seeds, irrigation, fertilisers, crop protection

Concept: Bacteria break down food to acids; pH below 5.5 corrodes tooth enamel.

1. Toothpaste is basic and neutralises this excess acid.
2. This prevents tooth decay; B, C and D describe acidic behaviour.

Yaad rakhein: Tooth enamel is calcium hydroxyapatite (calcium phosphate) – hardest substance in the body.

Answer: (A) To neutralise the acid formed in the mouth after eating food

Concept: Speed = frequency × wavelength.

1. $\lambda =v÷f=440÷220$.
2. $\lambda =2$ m.

Yaad rakhein: Frequency depends on the source and stays the same in any medium; speed and wavelength change.

Answer: (C) 2 m

Concept: Add atomic masses of all atoms in the formula (CaCl₂ has 1 Ca and 2 Cl).

1. Ca = 40 u, Cl = 35.5 u.
2. $40+2\times 35.5=40+71=111$ u.

Yaad rakhein: 'Formula unit mass' is used for ionic compounds like NaCl (58.5 u), CaCl₂ (111 u).

Answer: (B) Atomic mass of Ca + (2 × atomic mass of Cl) = 40 + 71 = 111 u

Concept: Carbon can reduce only oxides of metals less reactive than itself.

1. Mg is more reactive than carbon, so C cannot remove oxygen from MgO.
2. Highly reactive metals (Na, Mg, Ca, Al) are obtained by electrolytic reduction of molten compounds.

Yaad rakhein: Carbon reduces oxides of middle-reactivity metals like Zn, Fe, Pb (e.g. ZnO + C → Zn + CO).

Answer: (D) Carbon is less reactive than magnesium.

Concept: Of 16 essential nutrients, C, H, O come from air and water; the other 13 come from soil.

1. These 13 include 6 macro-nutrients (N, P, K, Ca, Mg, S) and 7 micro-nutrients (Fe, Mn, B, Zn, Cu, Mo, Cl).
2. So both macro- and micro-nutrients come from the soil.

Yaad rakhein: Macro-nutrients are needed in large amounts, micro-nutrients in very small amounts.

Answer: (A) soil ; soil

Concept: Exchange of ions between two compounds.

1. AgNO₃ + NaCl → AgCl↓ + NaNO₃: Ag⁺ and Na⁺ swap partners; white AgCl precipitate forms.
2. A, C and D are combination reactions (two reactants → one product).

Trick: One product only = combination; two compounds swapping partners = double displacement.

Answer: (B) AgNO₃ + NaCl → AgCl + NaNO₃

Concept: Heights above the principal axis are positive, below are negative.

1. A real image formed by a lens is inverted, i.e., below the axis.
2. So h' is taken negative (and magnification m = h'/h is negative).

Yaad rakhein: Virtual, erect images have positive h' and positive m.

Answer: (D) Negative, as it is below the axis

Concept: Desert plants keep stomata closed by day to save water.

1. They take in CO₂ at night and store it as an intermediate (acid).
2. In daytime, light energy is used to make carbohydrates from this stored CO₂.

Yaad rakhein: This is CAM (Crassulacean Acid Metabolism), seen in cacti, pineapple.

Answer: (C) Carbon dioxide uptake occurs at night and carbohydrates are synthesized during the day.

Concept: Complex tissues have more than one type of cell; xylem and phloem are complex.

1. Xylem (tracheids, vessels, xylem parenchyma, fibres) conducts water and minerals.
2. Phloem carries food; parenchyma and collenchyma are simple tissues.

Trick: X for 'water' – Xylem eXports water up; Phloem = food.

Answer: (B) Xylem

Concept: Acceleration is zero only if both speed and direction stay constant.

1. Car at constant speed on a straight road → velocity constant → a = 0.
2. Speeding up, taking off, ball thrown up → velocity changes → a ≠ 0.

Yaad rakhein: Uniform circular motion has constant speed but is still accelerated (direction changes).

Answer: (C) A car moving with constant speed on a straight road

Concept: Eukaryotes have a membrane-bound nucleus; prokaryotes have only a nucleoid.

1. Nucleoid = region with naked DNA and no nuclear membrane.
2. Found in bacteria → prokaryotic cell. Plant and animal cells are eukaryotic.

Yaad rakhein: Pro = before, karyon = nucleus: prokaryotes have no true nucleus.

Answer: (C) Prokaryotic Cell

Concept: Thomson: positive sphere with electrons embedded (plum pudding / watermelon).

1. Statement 1 true; Statement 3 true – watermelon: red part = positive charge, seeds = electrons.
2. Statement 2 false – nucleus and neutrons were not part of this model (nucleus: Rutherford 1911, neutron: Chadwick 1932).

Yaad rakhein: Thomson's model said the atom is electrically neutral as charges are equal.

Answer: (D) Only 1 and 3

Concept: A zig-zag line = resistor; an arrow across it = its value can be varied.

1. Symbol shows a resistor with a diagonal arrow → variable resistance (rheostat).
2. Battery = long and short parallel lines; closed switch = (•) key; wire = plain line.

Yaad rakhein: A rheostat is used to change current in a circuit without changing the source voltage.

Answer: (A) Variable resistance or rheostat

Concept: Reactivity with water: Na > Ca > Mg.

1. Ca + 2H₂O → Ca(OH)₂ + H₂: reacts with cold water, less violently than Na.
2. Mg barely reacts with cold water (reacts with hot water/steam).
3. Bubbles of H₂ stick to Ca, so it starts floating.

Yaad rakhein: Products with cold water are hydroxide + H₂; metals reacting with steam give oxide + H₂.

Answer: (A) Calcium reacts less vigorously than sodium but more than magnesium, forming calcium hydroxide and hydrogen gas.

Concept: Cartilage is a flexible connective tissue with a solid matrix of protein and sugars.

1. It is found in the ear pinna, nose tip, trachea, larynx and at ends (joint surfaces) of bones.
2. It smoothens bone surfaces at joints; bone is rigid, adipose stores fat.

Yaad rakhein: Areolar tissue fills spaces inside organs and lies between skin and muscles.

Answer: (C) Cartilage

Concept: $\frac{1}{v}+\frac{1}{u}=\frac{1}{f}$; for a convex mirror $f=+\frac{R}{2}$.

1. $f=+\frac{4}{2}=+2$ m; $u=-6$ m.
2. $\frac{1}{v}=\frac{1}{f}-\frac{1}{u}=\frac{1}{2}+\frac{1}{6}=\frac{4}{6}\to v=+1.5$ m.
3. Positive v → image behind the mirror (virtual, erect, diminished).

Trick: Convex mirror image is always virtual and behind the mirror – option D is out instantly.

Answer: (A) Image is formed at 1.5 m behind the mirror

Concept: Mass % = mass of solute ÷ (solute + solvent) × 100.

1. Doubling both: $\frac{2a}{2a+2b}=\frac{a}{a+b}$.
2. The ratio does not change, so mass % stays the same.

Trick: Scaling numerator and denominator by the same factor never changes a fraction.

Answer: (A) Remain the same

Concept: Path of urine: kidney → ureter → urinary bladder → urethra.

1. Urine made in the nephrons passes through the ureters.
2. It is stored in the urinary bladder until released through the urethra.

Trick: Order 'K-U-B-U': Kidney, Ureter, Bladder, Urethra.

Answer: (B) ureters; urinary bladder

Concept: W = F × s × cosθ.

1. If s = 0, W = F × 0 = 0, however large the force.
2. Example: pushing a wall that does not move – no work done.

Yaad rakhein: Work is also zero when force ⟂ displacement (θ = 90°), e.g. a coolie carrying a load on a level road.

Answer: (A) Zero