Q&A: practice questions with answers

Concept: Mass percent (w/w) $=\frac{\text{mass of solute}}{\text{mass of solution}}\times 100$, where mass of solution = solute + solvent.

1. Mass of solution $=15+585=600\text{g}$.
2. Mass $\%=\frac{15}{600}\times 100=2.5\%$.

Trick: Always divide by the total (solute + solvent), not by the solvent alone – $\frac{15}{585}$ would be a wrong 2.56%.

Answer: (A) 2.5%

Concept: "Vande Mataram" was composed by Bankim Chandra Chattopadhyay on 7 November 1875. Its 150th anniversary (7 Nov 2025) was marked by a year-long national celebration.

1. The Prime Minister launched the year-long commemoration at Indira Gandhi Indoor Stadium, New Delhi, on 7 November 2025; the event was organised by the Ministry of Culture.
2. The Ministry of Culture handles such national commemorations (e.g. Azadi Ka Amrit Mahotsav) – not Education, Sports or Home.

Yaad rakhein: National commemorations of songs, leaders and heritage = Ministry of Culture.

Answer: (C) Ministry of Culture

Concept: José Antonio Kast, leader of Chile's Republican Party, won the December 2025 run-off and was sworn in as President of Chile on 11 March 2026, succeeding Gabriel Boric.

1. Chile's capital is Santiago; presidential terms there run four years with the oath taken in March.
2. Argentina's president is Javier Milei and Brazil's is Lula da Silva – not Kast.

Yaad rakhein: Kast → Chile (both have the "Santiago" link: Kast took oath in Valparaíso, seat of Chile's Congress).

Answer: (C) Chile

Concept: The Preamble declares India a Sovereign, Socialist, Secular, Democratic Republic. "Republic" means the head of state (President) is elected, not a hereditary monarch.

1. The President of India is indirectly elected for five years (Article 54) – hence a republic, unlike Britain where the monarch is hereditary.
2. Sovereign = free from external control; Secular = no state religion; Socialist = social and economic justice.

Yaad rakhein: Republic = "elected head"; Democratic = "elected government". Both together = elected at every level.

Answer: (B) Republic

Concept: A population pyramid shows age groups (young at the bottom, old at the top). The width of the base reflects birth rate; the width of the top reflects how many people survive to old age (life expectancy).

1. Narrow base → few children being born → low birth rate.
2. Wide top → a large share of elderly people → high life expectancy (low death rate). Example: Japan.
3. A wide base with a narrow top (option C) is the expanding pyramid of a developing country.

Yaad rakhein: Base = births, Top = old-age survival. "Upside-down" pyramid = ageing, developed country.

Answer: (D) Low birth rates and high life expectancy

Concept: Gelatinization is the process in which starch granules absorb water on heating, swell and burst, turning the mixture into a thick gel – this is how rice, potatoes and flour-based sauces soften/thicken.

1. Heating starch with water (about $60$–${70}^{\circ }\text{C}$) breaks the granule structure → gelatinization.
2. Caramelization is browning of sugar on dry heat; saponification is fat + alkali → soap; fermentation is microbial action on sugars.

Yaad rakhein: Starch + water + heat = "Gel" → Gelatinization (think of thick gravy or kheer).

Answer: (A) Gelatinization

Concept: Sir Syed Ahmad Khan's Aligarh Movement (MAO College, 1875) promoted modern Western-style scientific education among Muslims, while Swami Dayananda's Arya Samaj (1875) called for a return to the Vedas ("Back to the Vedas").

1. Aligarh Movement: Scientific Society (1864), MAO College Aligarh – embraced English education and rational outlook.
2. Arya Samaj: rejected idol worship and caste rigidity, ran gurukuls and DAV schools for Vedic plus modern learning.
3. Options A, C and D wrongly say Aligarh opposed science/modern learning – the opposite of its aim.

Yaad rakhein: Aligarh = "Western education"; Arya Samaj = "Back to the Vedas". Both founded in 1875.

Answer: (B) Aligarh Movement supported Western-style education, while Arya Samaj promoted Vedic studies.

Concept: Seismic shadow zone is the region on Earth's surface where seismographs do not record a particular wave after an earthquake. S-waves (transverse) cannot pass through liquids, so they are absent beyond ${105}^{\circ }$ from the epicentre.

1. S-wave shadow zone: beyond ${105}^{\circ }$ on the opposite side – covers more than 40% of the surface; proves the outer core is liquid.
2. P-wave shadow zone: between ${105}^{\circ }$ and ${145}^{\circ }$ (P-waves refract through the core).

Yaad rakhein: S = "Shear/Secondary" – Stops in liquid → big Shadow zone. P = Primary – Passes through all media.

Answer: (C) Shadow zone

Concept: Fundamental Duties (Part IV-A, Article 51A) were added on the recommendation of the Swaran Singh Committee (1976) by the 42nd Constitutional Amendment Act, 1976, borrowing the idea from the USSR.

1. Originally 10 duties were added in 1976; the 11th (education of children aged 6–14) came by the 86th Amendment, 2002.
2. 44th Amendment (1978) undid parts of the 42nd; 40th and 48th are unrelated.

Yaad rakhein: "42 = Mini Constitution" – added Fundamental Duties, and the words Socialist, Secular, Integrity to the Preamble.

Answer: (A) 42^nd Amendment

Concept: In April 2025 the Union Cabinet approved the 166.8 km Shillong–Silchar 4-lane greenfield high-speed access-controlled corridor (part of NH-6) at a cost of about ₹22,864 crore.

1. The corridor runs from Mawlyngkhung near Shillong (Meghalaya) to Panchgram near Silchar (Assam), so it passes through Meghalaya and Assam.
2. It is built on hybrid annuity mode and will cut travel time, also improving access to Tripura, Mizoram and Manipur via Silchar.

Yaad rakhein: Shillong (Meghalaya) → Silchar (Assam): the two end-cities tell you the two states.

Answer: (C) Meghalaya and Assam

Concept: The 7th meeting of the National Board for Wildlife (NBWL), chaired by PM Narendra Modi, was held on 3 March 2025 (World Wildlife Day) at Gir National Park, Junagadh, Gujarat.

1. At Gir the PM also announced a new National Referral Centre for Wildlife (Junagadh) and extension of Project Cheetah to Gandhi Sagar (MP) and Banni (Gujarat).
2. Gir is the only natural home of the Asiatic lion – the previous (6th) NBWL meeting was at Pench in 2012.

Yaad rakhein: 2025 NBWL meet = Gir (lions), announced on World Wildlife Day, 3 March.

Answer: (B) Gir National Park

Concept: The Konark Sun Temple (Odisha), a UNESCO World Heritage Site, was built around 1250 CE by King Narasimhadeva I of the Eastern Ganga dynasty.

1. It is designed as a giant chariot of the Sun god with 24 carved wheels and seven horses; Europeans called it the "Black Pagoda".
2. Chandragupta II and Harshavardhana are ancient rulers unrelated to Konark; Ashoka is linked to Kalinga war and stupas.

Yaad rakhein: Konark = Narasimhadeva I (Ganga dynasty); Lingaraj temple (Bhubaneswar) = Somavamshi kings.

Answer: (C) Narasimhadeva I

Concept: The Revolt of 1857 began at Meerut on 10 May 1857 when sepoys of the Bengal Army mutinied over the greased cartridges, then marched to Delhi and proclaimed Bahadur Shah Zafar as emperor.

1. Mangal Pandey had fired at officers in Barrackpore on 29 March 1857, but the organised outbreak started at Meerut.
2. Delhi was the centre the rebels captured next; Kanpur (Nana Saheb) and Lucknow (Begum Hazrat Mahal) rose later.

Yaad rakhein: "10 May, Meerut" – start; Barrackpore = Mangal Pandey (spark), Delhi = capital of revolt.

Answer: (B) Meerut

Concept: The Hooghly industrial belt (West Bengal), stretching from Bansberia to Birlanagar along the Hooghly river, grew around the port of Kolkata and is India's most important port-based industrial region (jute, engineering, chemicals).

1. Kolkata port + Hooghly navigation + coal from Raniganj and jute from the delta made this belt flourish from the 19th century.
2. Chotanagpur is mineral-based (iron and steel); Ahmedabad–Vadodara is textile/petrochemical and inland; Hyderabad–Bengaluru is a modern IT/electronics corridor.

Yaad rakhein: Hooghly = "port + jute"; Chotanagpur = "coal + iron"; Mumbai–Pune = cotton textiles.

Answer: (C) Hooghly industrial belt

Concept: In October 2024 Kerala's Motor Vehicles Department began enforcing child-safety rules (child restraint systems/seat-belts in cars, helmets for children on two-wheelers) in phases.

1. Phase 1 (October 2024) was a social-media awareness campaign explaining the rules to parents.
2. Only after awareness did later phases move to stopping and warning violators and then to penalties – so enforcement with fines (option B) was not the first step.

Yaad rakhein: Kerala MVD style: "first educate, then warn, then fine" – awareness always comes first.

Answer: (A) Social media awareness campaign

Concept: Equal areas: $l\times b=\pi r^2$, then perimeter of circle $=2\pi r$.

1. Area of rectangle $=55\times 70=3850{\text{m}}^2$.
2. $\frac{22}{7}{r}^2=3850\Rightarrow r^2=3850\times \frac{7}{22}=1225\Rightarrow r=35\text{m}$.
3. Circumference $=2\times \frac{22}{7}\times 35=220\text{m}$.

Trick: $3850=22\times 175=22\times 7\times 25$, so $r^2=7^2\times 5^2$ and $r=35$ at a glance.

Answer: (C) 220

Concept: If $a+b+c=0$ then $a^3+b^3+c^3=3abc$.

1. Here $22+(-18)+(-4)=0$.
2. So the sum $=3\times 22\times (-18)\times (-4)=3\times 22\times 72$.
3. $=66\times 72=4752$.

Trick: Whenever the three bases add to zero, never cube them – just multiply $3abc$.

Answer: (C) 4752

Concept: Form two linear equations from the two time points.

1. Let present ages be $S$ (Shyam) and $R$ (Rajat). 4 years ago: $S-4=7(R-4)\Rightarrow S=7R-24$.
2. After 8 years: $S+8=3(R+8)\Rightarrow S=3R+16$.
3. $7R-24=3R+16\Rightarrow 4R=40,R=10$, so $S=7\times 10-24=46$.

Trick: Check: 4 years ago 42 and 6 (ratio 7:1); after 8 years 54 and 18 (ratio 3:1). Both fit.

Answer: (A) 46 years

Concept: Same distance both ways: average speed $=\frac{2xy}{x+y}$.

1. $x=32,y=24$.
2. Average $=\frac{2\times 32\times 24}{32+24}=\frac{1536}{56}$.
3. $=27.428\dots \approx 27.43\text{km/h}$.

Trick: The 48 km distance is a distractor – for equal distances it cancels out.

Answer: (D) 27.43 km/hr

Concept: Length of train $=$ relative speed $\times$ time; relative speed (same direction) $=v-u$.

1. Let train speed be $v$ km/h. $L=(v-5)\times \frac{5}{18}\times 18=5(v-5)$.
2. Also $L=(v-7)\times \frac{5}{18}\times 20=\frac{50(v-7)}{9}$.
3. $45(v-5)=50(v-7)\Rightarrow 5v=125,v=25$; $L=5\times 20=100\text{m}$.

Trick: Convert km/h to m/s with $\times \frac{5}{18}$ first; the 18 s cancels neatly.

Answer: (D) 100