Q&A: practice questions with answers

Concept: The gold-foil (alpha-particle scattering) experiment revealed the nucleus.

1. Ernest Rutherford (1911) fired alpha particles at thin gold foil; most passed straight, a few deflected sharply.
2. He concluded that the atom's positive charge and mass sit in a tiny, dense centre – the nucleus.
3. Dalton gave atomic theory, Boyle the gas law, Mendeleev the periodic table.

Yaad rakhein: Gold foil → Rutherford → nucleus; Cathode rays → Thomson → electron.

Answer: (A) Ernest Rutherford

Concept: Lothal (Gujarat) was a Harappan port town on the Bhogavo–Sabarmati region near the Gulf of Khambhat.

1. Its most famous feature is the brick dockyard, considered one of the world's earliest tidal docks.
2. The dockyard shows sea trade of the Indus people with distant regions.
3. The Great Bath is at Mohenjo-daro; large granaries are linked to Harappa and Mohenjo-daro.

Yaad rakhein: Lothal = dockyard; Mohenjo-daro = Great Bath; Kalibangan = ploughed field.

Answer: (B) Dockyards

Concept: Proteins are the body-building nutrients.

1. Proteins supply amino acids used to build new cells and repair damaged tissue – needed for growth and wound healing.
2. Carbohydrates and fats mainly give energy; vitamins and minerals are protective nutrients that regulate body processes.
3. Hence growth and healing are chiefly supported by proteins.

Yaad rakhein: Proteins = body-builders; Carbs/Fats = energy-givers; Vitamins/Minerals = protectors.

Answer: (C) Proteins

Concept: Famous Indian musicians are asked with their instruments.

1. Ustad Bismillah Khan of Varanasi made the shehnai a concert instrument; he played it at the Red Fort on 15 August 1947.
2. He received the Bharat Ratna in 2001.
3. Sarod – Amjad Ali Khan; Tabla – Zakir Hussain; Sitar – Ravi Shankar.

Yaad rakhein: Bismillah = Shehnai; Hariprasad Chaurasia = Flute; Shivkumar Sharma = Santoor.

Answer: (B) Shehnai

Concept: Windows offers Shut down, Restart, Sleep and Hibernate, each handling open work differently.

1. Shut down closes all apps and data and switches the PC off completely.
2. Saving the session to disk then powering off is Hibernate (option A).
3. Low-power state with apps kept in memory is Sleep/stand-by (options C and D).

Trick: Shut down = everything closed, power off; Sleep = RAM; Hibernate = disk.

Answer: (B) All apps and data are closed and the PC powers off completely

Concept: Article 323A (added by the 42nd Amendment, 1976) lets Parliament create administrative tribunals for service matters.

1. Using this power Parliament passed the Administrative Tribunals Act, 1985.
2. The Central Administrative Tribunal (CAT) was set up under it on 1 November 1985 to decide service disputes of central government employees.
3. The other options are not the parent law of CAT.

Yaad rakhein: 323A → Administrative tribunals (CAT, 1985); 323B → other tribunals.

Answer: (C) Administrative Tribunals Act, 1985

Concept: The Right to Constitutional Remedies lets a person go directly to the Supreme Court when a Fundamental Right is violated.

1. Article 32 gives this right; the Supreme Court can issue writs – habeas corpus, mandamus, prohibition, certiorari, quo warranto.
2. Dr B.R. Ambedkar called Article 32 the 'heart and soul' of the Constitution.
3. Article 226 is the High Courts' writ power (wider, but not a Fundamental Right).

Yaad rakhein: 32 → Supreme Court writs (FR); 226 → High Court writs.

Answer: (C) Article 32

Concept: A more reactive metal displaces a less reactive metal from its salt solution.

1. $\text{Fe}+{\text{CuSO}}_4\to {\text{FeSO}}_4+\text{Cu}$
2. Blue solution turns light green (${\text{FeSO}}_4$) and reddish-brown copper deposits on the iron.
3. This happens because iron is more reactive than copper (Fe is above Cu in the reactivity series).

Yaad rakhein: Reactivity order: K Na Ca Mg Al Zn Fe Pb H Cu Hg Ag Au – a higher metal pushes out a lower one.

Answer: (D) Iron is more reactive than copper

Concept: Article 21 – Right to Life and Personal Liberty – has been read to include dignity, health and reproductive rights.

1. In May 2025 the Supreme Court (K. Umadevi v. State of Tamil Nadu) held that maternity leave is part of a woman's reproductive rights and allowed it to a government employee for her third child.
2. The Court linked these reproductive rights to Article 21.
3. Article 14 is equality, Article 19 freedoms, Article 27 freedom from religious taxes.

Yaad rakhein: Dignity, privacy, health, reproductive choice – all flow from Article 21.

Answer: (C) Article 21

Concept: The small intestine has three parts: duodenum, jejunum and ileum.

1. The duodenum is the first, C-shaped part; the common bile duct (bile + pancreatic juice) opens into it.
2. Bile emulsifies fats; pancreatic juice digests proteins, carbohydrates and fats.
3. Jejunum and ileum mainly absorb food; the colon is part of the large intestine.

Yaad rakhein: Order: Duodenum → Jejunum → Ileum ('DJI'); juices enter at D.

Answer: (A) Duodenum

Concept: The Wahabi Movement was an Islamic revivalist and anti-British movement of the 19th century.

1. It was inspired by Syed Ahmad of Rae Bareli, and Patna (Bihar) became its main centre.
2. Patna leaders such as Vilayat Ali and Inayat Ali organised it; the British suppressed it through the Wahabi trials of the 1860s–70s.
3. Bengal is linked with the Faraizi Movement – the tempting wrong option.

Yaad rakhein: Wahabi → Patna (Bihar); Faraizi → Bengal; Kuka → Punjab.

Answer: (C) Bihar

Concept: Muhammad bin Tughlaq (1325–51) is known for bold experiments.

1. Facing a shortage of silver, he introduced token currency – copper/brass coins to be valued like silver tankas.
2. People forged the coins at home, the scheme failed and the Sultan had to exchange them for real silver coins.
3. His other experiments: shifting the capital to Daulatabad and raising taxes in the Doab.

Yaad rakhein: Tughlaq's 'token' = copper coin with silver value.

Answer: (A) Token currency

Concept: 7-bit ASCII has $2^7=128$ codes (0 to 127): control codes plus printable characters.

1. The control-character block is codes 0 to 31, i.e. $31-0+1=32$ codes (NUL, TAB, LF, CR, ESC …).
2. Codes 32 to 126 are the 95 printable characters (space, digits, letters, symbols).
3. So the standard control block contains 32 characters; 64 and 16 do not fit this layout.

Yaad rakhein: ASCII: $0$–$31$ control, $32$–$126$ printable, total $128$.

Answer: (C) 32

Concept: Hertz means cycles per second; giga ($\text{G}$) means ${10}^9$ (one billion).

1. $1\text{GHz}={10}^9$ cycles per second.
2. $3.5\text{GHz}=3.5\times {10}^9$ cycles per second.
3. That is 3.5 billion cycles every second.

Trick: kilo ${10}^3$ → mega ${10}^6$ → giga ${10}^9$ (thousand, million, billion).

Answer: (C) 3.5 billion cycles per second

Concept: The rigid lithosphere is broken into plates that rest on the asthenosphere.

1. The asthenosphere (upper mantle, roughly 100–400 km deep) is hot, weak and partially molten, so it flows slowly like plastic.
2. This ductile layer lets the lithospheric plates slide over it; convection currents in it help drive plate motion.
3. It is not water, not rigid, and the magnetic field comes from the liquid outer core.

Yaad rakhein: Astheno = 'weak' (Greek) – the soft layer the plates ride on.

Answer: (A) It is partially molten and allows plates to move

Concept: SP per lemon stays fixed by the price; find CP per lemon from the loss, then the SP needed for the gain.

1. 5 lemons for ₹1 → SP of 1 lemon $=\frac{1}{5}=0.2$.
2. Loss $34\%$: $0.2=0.66\times CP\Rightarrow CP=\frac{0.2}{0.66}=\frac{10}{33}$.
3. For $10\%$ gain, SP $=\frac{10}{33}\times 1.1=\frac{11}{33}=\frac{1}{3}$.
4. So ₹1 buys $3$ lemons.

Trick: $\text{New count}=\text{old count}\times \frac{100-\text{loss}}{100+\text{gain}}=5\times \frac{66}{110}=3$.

Answer: (C) 3

Concept: Form an equation with the original CP $=x$.

1. Original SP $=1.21x$.
2. New CP $=x+50$, new SP $=1.21x-69$, profit $13.6\%$: $1.21x-69=1.136(x+50)$.
3. $1.21x-1.136x=56.8+69\Rightarrow 0.074x=125.8$.
4. $x=\frac{125.8}{0.074}=1700$.

Trick: Check with option: CP 1700 → SP 2057; new CP 1750, new SP 1988, profit $238=13.6\%$ of 1750 ✓.

Answer: (B) 1,700

Concept: $\text{Average speed}=\frac{\text{Total distance}}{\text{Total time}}$ (never the average of speeds).

1. Walking time $=\frac{6}{6}=1$ h; running time $=\frac{18}{9}=2$ h.
2. Total distance $=24$ km, total time $=3$ h.
3. Average speed $=\frac{24}{3}=8\text{km/h}$.

Yaad rakhein: Distances unequal → always compute time for each part separately.

Answer: (D) 8

Concept: Mode = the value occurring most often.

1. Count repeats: 46 appears $3$ times (positions 10, 12, 17).
2. 43, 41 and 45 appear $2$ times each; all others once.
3. Highest frequency → mode $=46$.

Trick: Tally only values that repeat; a quick tick-mark count avoids rewriting the whole list.

Answer: (A) 46

Concept: Let the numbers be $5x$ and $7x$; transfer keeps the total same.

1. After transfer: A $=5x+28$, B $=7x-28$.
2. Ratio $1:1$: $5x+28=7x-28\Rightarrow 2x=56\Rightarrow x=28$.
3. A $=140$, B $=196$.

Trick: Difference $7x-5x=2x$ must be covered by moving $28$ twice (28 out of B and 28 into A) → $2x=56$.

Answer: (C) 140 in A, 196 in B