Q&A: practice questions with answers

Concept: Interference and diffraction obey the law of conservation of energy – light energy is neither created nor destroyed, only redistributed.

1. Energy missing from the dark fringes appears in the bright fringes; the average intensity over the whole pattern stays the same as without superposition.
2. So options saying energy increases, decreases or reduces are wrong.

Yaad rakhein: Fringes = redistribution of energy, not loss or gain.

Answer: (C) It is redistributed

Concept: The Environment Audit Rules, 2025 were notified by MoEFCC on 29 August 2025 under the Environment (Protection) Act, 1986.

1. The rules create a system of registered Environment Auditors and Environment Audit Designated Agencies to independently verify compliance with environmental conditions and consents.
2. The EPA 1986 is the umbrella law under which such rules (EIA, E-waste, Plastic Waste etc.) are issued; the other Acts cover forests, wildlife and air separately.

Yaad rakhein: Any new "environment …rules" from MoEFCC → Environment (Protection) Act, 1986.

Answer: (A) Environment (Protection) Act, 1986

Concept: Peninsular rivers rise in the plateau (Western Ghats, Vindhya–Satpura, Chhota Nagpur); Himalayan rivers rise in the Himalayas.

1. Ganga originates at the Gangotri glacier (Bhagirathi) in Uttarakhand – a Himalayan river, perennial and snow-fed.
2. Narmada (Amarkantak), Krishna (Mahabaleshwar) and Godavari (Trimbakeshwar) are peninsular, rain-fed rivers.

Yaad rakhein: Himalayan trio – Indus, Ganga, Brahmaputra; everything south of the Vindhyas is peninsular.

Answer: (D) Ganga

Concept: The IMF, in its 2025 Article IV consultation report on India, reclassified the de facto exchange-rate regime from "stabilised arrangement" to "crawl-like arrangement".

1. The IMF publishes the AREAER classification of exchange regimes; it noted that the rupee moved within a narrow band against the dollar between Dec 2022 and Oct 2024, then shifted.
2. The RBI maintains that it intervenes only to curb excess volatility and has no target level.

Yaad rakhein: Exchange-rate regime classification = IMF (Article IV / AREAER), not World Bank or ADB.

Answer: (A) International Monetary Fund (IMF)

Concept: Articles 168–212 (Part VI, Chapter III) deal with the State Legislature; Article 182 provides for the Chairman and Deputy Chairman of the Legislative Council.

1. Art. 178 – Speaker and Deputy Speaker of the Assembly; Art. 182 – Chairman and Deputy Chairman of the Council (mirror provision).
2. Art. 170 – composition of Legislative Assemblies; Art. 176 – special address by the Governor; Art. 191 – disqualification for membership.

Yaad rakhein: Parliament Art. 89 (Rajya Sabha Chairman) ↔ State Art. 182 (Council Chairman).

Answer: (A) Chairman and Deputy Chairman of the State Legislative Council

Concept: Koli is the folk dance of the Koli fishing community of the Konkan coast, Maharashtra (also Goa).

1. Men and women dance in rows imitating rowing boats and casting nets; it is performed at festivals like Narali Purnima and Holi.
2. Other Maharashtra folk forms: Lavani, Tamasha, Povada, Dhangari Gaja.

Yaad rakhein: Koli = Mumbai's original fisherfolk → Maharashtra.

Answer: (C) Maharashtra

Concept: A quintal is a unit of mass (weight) equal to 100 kg; 10 quintals = 1 tonne.

1. It is commonly used in India for agricultural produce – MSP of wheat, paddy etc. is quoted per quintal.
2. Temperature → kelvin/°C, length → metre, volume → litre/cubic metre.

Yaad rakhein: 1 quintal = 100 kg = 1 "kwintal" of grain at the mandi.

Answer: (A) Weight

Concept: Ctrl+Z undoes the last action in almost every application (Windows/Linux); Ctrl+Y redoes it.

1. Ctrl+X = cut, Ctrl+U = underline, Ctrl+E = centre-align (in Word).
2. On Mac the equivalent is Cmd+Z.

Yaad rakhein: Z is the last letter – "undo the last thing"; X looks like scissors – cut.

Answer: (D) Ctrl+Z

Concept: The Chalukyas and Rashtrakutas ran a decentralised, feudal-type administration – samantas (feudatory chiefs) held land grants and supplied troops.

1. Feudatories such as the Gangas, Banas and Shilaharas administered their territories and brought their armies when the overlord campaigned, combining military and administrative roles.
2. Temples did not recruit soldiers, district heads were not rotated annually, and governance was not fully centralised – power was shared with hereditary chiefs.

Yaad rakhein: Deccan kingdoms = samanta (feudatory) system; Cholas later tightened central control.

Answer: (A) Feudatory chiefs were assigned military and administrative duties

Concept: "Right to Information: Master Key to Good Governance" is the first report (June 2006) of the Second Administrative Reforms Commission, chaired by M. Veerappa Moily.

1. The 2nd ARC (2005–09) submitted 15 reports; others include "Unlocking Human Capital", "Ethics in Governance" and "Crisis Management".
2. The 1st ARC (1966–70, Morarji Desai, later K. Hanumanthaiah) predates the RTI Act, 2005, so it could not have reported on RTI; Sarkaria and Punchhi Commissions dealt with Centre–State relations.

Yaad rakhein: RTI Act 2005 → 2nd ARC's first report 2006 "Master Key to Good Governance".

Answer: (D) Administrative Reforms Commission (ARC) - 2

Concept: On 31 October 2025 Defence Minister Rajnath Singh and US Secretary of War Pete Hegseth signed a 10-year India–US Framework for Major Defence Partnership in Kuala Lumpur.

1. The signing took place on the sidelines of the ADMM-Plus / ASEAN–India Defence Ministers' Informal Meeting hosted by Malaysia.
2. It replaces the 2015 framework and covers co-production, technology sharing, intelligence and interoperability.

Yaad rakhein: Kuala Lumpur, Oct 2025 – Rajnath + Hegseth – 10-year India–US defence framework.

Answer: (D) United States of America

Concept: The WMO Greenhouse Gas Bulletin (2023 data) reported carbon dioxide at 420 ppm – 151% of its pre-industrial (1750) level.

1. Methane stood at about 265% and nitrous oxide at about 125% of pre-industrial levels in the same bulletin.
2. CO${}_2$ is the single most important long-lived greenhouse gas, contributing about two-thirds of warming; the 2024-data bulletin (released Oct 2025) put it at 152%.

Yaad rakhein: CO${}_2$ ≈ 150%, CH${}_4$ ≈ 265%, N${}_2$O ≈ 125% of pre-industrial.

Answer: (B) Carbon dioxide

Concept: The Rangarajan Expert Group, set up in 2012 to review the Tendulkar methodology, submitted its report in June 2014.

1. It raised the poverty line to ₹47 per day (urban) and ₹32 per day (rural) and estimated 29.5% of Indians below the poverty line in 2011-12.
2. Tendulkar Committee reported in 2009; Lakdawala in 1993.

Yaad rakhein: Lakdawala 1993 → Tendulkar 2009 → Rangarajan 2014.

Answer: (B) 2014

Concept: The Environment Audit Rules, 2025 set up a nationwide framework for independent environmental audits, i.e. environmental accountability and compliance.

1. Registered Environment Auditors, certified by an Environment Audit Designated Agency, will verify compliance with environmental clearances, consents and waste-management rules.
2. The rules do not impose a tax, run a water campaign or a plantation programme.

Yaad rakhein: "Audit" = checking compliance → accountability framework.

Answer: (C) A framework for environmental accountability

Concept: Computer-generated imagery (CGI), VFX and animation in films are applications of computers in the entertainment industry.

1. Studios use render farms and software like Maya, Houdini and Blender to create special effects.
2. Accounting, banking and scientific research are different application areas; "scientific research only" is wrong because the context is films.

Yaad rakhein: Films, games, music, streaming → Entertainment application of computers.

Answer: (C) Entertainment

Concept: An operating system is the core resource manager – it allocates CPU time, memory, storage and I/O devices among programs and users.

1. It sits between hardware and application software, scheduling processes and managing files and devices.
2. Application logic belongs to apps, a peripheral device is hardware, and utilities are helper programs – none describe the OS's core role.

Yaad rakhein: OS = resource manager + interface between user/apps and hardware.

Answer: (D) resource manager

Concept: In December 2025 Qatar Airways named Hamad Ali Al-Khater as its new Group Chief Executive Officer.

1. He succeeded Engr. Badr Mohammed Al-Meer, who had led the airline since November 2023 after Akbar Al Baker.
2. Sheikh Mohammed bin Abdulrahman Al Thani is Qatar's Prime Minister; Mohamed bin Rashid Al Maktoum is the ruler of Dubai.

Yaad rakhein: Qatar Airways CEOs: Al Baker → Al-Meer (2023) → Al-Khater (Dec 2025).

Answer: (D) Hamad Ali Al-Khater

Concept: Fix the marked price as the base, find the cost price from the first sale, then compare the second selling price with that cost price.

1. Let marked price $M=130$ (a number divisible by 13 and 10). First SP $=\frac{4}{13}\times 130=40$.
2. Loss $30\%$ means $\text{SP}=0.7\text{CP}$, so $\text{CP}=\frac{40}{0.7}=\frac{400}{7}$.
3. New SP $=60\%$ of $130=78$. Profit $=78-\frac{400}{7}=\frac{146}{7}$.
4. Profit$\%=\frac{146/7}{400/7}\times 100=\frac{146}{4}=36.5\%$.

Trick: Both sales use the same CP, so $\frac{{\text{SP}}_2}{{\text{SP}}_1}=\frac{100+p}{100-30}$: $\frac{78}{40}=\frac{100+p}{70}\Rightarrow p=36.5$.

Answer: (A) $36.5\%$

Concept: Solve each bracket separately, then combine. Convert decimals to fractions to cancel quickly.

1. $3.6÷\frac{3}{5}=3.6\times \frac{5}{3}=6$.
2. $\frac{7}{3}\times \frac{2.4}{1.4}=\frac{7}{3}\times \frac{12}{7}=4$.
3. $\frac{5}{6}+\frac{14}{12}=\frac{5}{6}+\frac{7}{6}=2$.
4. Total $=6+4-2=8$.

Trick: $\frac{2.4}{1.4}=\frac{24}{14}=\frac{12}{7}$ – the 7 cancels with $\frac{7}{3}$ instantly.

Answer: (A) 8

Concept: If two sums become equal after $n$ and $n+1$ years at the same rate, the first sum is already one year "ahead": $P_1=P_2(1+\frac{r}{100})$.

1. $P(1.08{)}^{18}=G(1.08{)}^{19}\Rightarrow P=1.08G$.
2. $P:G=108:100=27:25$.
3. Gopal $=\frac{25}{52}\times 1404=25\times 27=675$.

Trick: Ratio of shares = $(100+r):100$ in favour of the one who invests for fewer years. Here $27:25$, and $1404÷52=27$.

Answer: (B) 675