Explanation: Albert Einstein received the Nobel Prize in Physics in 1921 for his discovery of the photoelectric effect, not for his famous theory of relativity. In the photoelectric effect, when light of a certain frequency falls on a metal surface, it emits electrons. Einstein explained this phenomenon by proposing that light is made up of discrete packets of energy called photons. The energy of each photon is given by E = hν, where h is Planck’s constant and ν is the frequency of light. This discovery laid the foundation for quantum physics and modern electronics.

Explanation: The ATM (Automated Teller Machine) was invented by John Shepherd-Barron in 1967. He designed the first cash dispensing machine, which was installed by Barclays Bank in London, UK. The first ATM used special paper vouchers impregnated with a radioactive compound instead of plastic cards. The idea revolutionized the banking sector by allowing people to withdraw money anytime without visiting a bank counter. Modern ATMs now use magnetic or chip-based cards, PIN authentication, and networked systems for secure transactions.

Explanation: A Local Area Network (LAN) is a network of computers and peripherals confined to a small geographical area, such as a home, school, or office building. It enables resource sharing, file transfer, and communication among connected devices within the limited range.

Explanation: The term "Ozone hole" does not mean an actual hole but refers to a significant decrease in the thickness of the ozone layer in the Earth's stratosphere. This thinning occurs mainly over the Antarctic region during spring (September–November) due to chemical reactions involving chlorofluorocarbons (CFCs) and other ozone-depleting substances. These chemicals release chlorine and bromine atoms, which destroy ozone (O₃) molecules. The thinning allows more harmful ultraviolet (UV) radiation to reach the Earth's surface, causing health and environmental hazards.

Explanation: Gamma rays are the most dangerous type of radiation because they have very high energy and strong penetrating power. They can pass through most materials, including human tissue, and may cause serious cellular and genetic damage. Proper shielding with dense materials like lead is required for protection.

Explanation: Gerontology is the branch of medical and biological science that deals with the study of aging and the diseases and problems specific to old age. It focuses on understanding the physical, mental, and social changes that occur in elderly individuals, as well as methods to promote healthy aging. Gerontology includes aspects of geriatrics, which specifically involves the medical care and treatment of elderly patients.

When iron rusts, its weight increases. This is because rusting is a chemical reaction between iron, oxygen, and moisture from the air, forming hydrated iron(III) oxide (Fe₂O₃·xH₂O). During this process, oxygen atoms from the air combine with the iron, adding extra mass to the metal surface in the form of rust. However, while the weight increases, the structural strength of the iron decreases due to corrosion.

Other options (for context)

• Decreases: Incorrect — mass increases due to the addition of oxygen.
• Remains the same: Incorrect — oxygen from air chemically adds to iron, increasing total mass.
• First increases and then decreases: Not applicable — in normal rusting, weight continues to increase until the surface flakes off.

Explanation: Ascorbic acid is not a member of the vitamin B complex; it is actually vitamin C. The vitamin B complex includes vitamins like thiamine (B₁), riboflavin (B₂), niacin (B₃), folic acid (B₉), and others that play important roles in metabolism and energy production.

The Green Revolution is associated with Agriculture. It refers to the period during the 1960s–70s when new technologies like high-yield variety (HYV) seeds, fertilizers, irrigation, and pesticides were introduced to boost food grain production, especially wheat and rice. It helped India achieve self-sufficiency in food production.

• Sericulture: Rearing of silkworms for silk.
• Fishery: Cultivation and harvesting of fish.
• Cultivation of bees: Known as apiculture, for honey production.

Argon (Ar) is an inert gas, also known as a noble gas. It belongs to Group 18 of the periodic table, whose elements are characterized by complete outer electron shells, making them chemically unreactive. Argon constitutes about 0.93% of the Earth's atmosphere and is widely used in electric bulbs, welding, and in creating inert environments for chemical reactions.

Other options (for context)

• Hydrogen: Highly reactive and combustible gas.
• Nitrogen: Relatively less reactive but not inert; forms compounds like ammonia.
• Oxygen: Highly reactive gas essential for combustion and respiration.