Explanation: Aerosols (such as those used in spray cans, refrigerants, and air conditioners) often contain chlorofluorocarbons (CFCs) and other halogen compounds. These chemicals rise to the stratosphere, where ultraviolet (UV) radiation breaks them down, releasing chlorine atoms. Each chlorine atom can destroy thousands of ozone (O₃) molecules, leading to ozone layer depletion. The thinning of the ozone layer allows more harmful UV rays to reach Earth, increasing the risk of skin cancer, eye damage, and affecting ecosystems.

Vitamin-B complex and Vitamin-C are water-soluble vitamins. This means they dissolve easily in water and are not stored in the body; hence, they must be consumed regularly through diet. Excess amounts of these vitamins are excreted through urine. Vitamin-B complex includes B₁ (Thiamine), B₂ (Riboflavin), B₃ (Niacin), B₆, B₁₂, and others that play key roles in metabolism and energy production. Vitamin-C (Ascorbic acid) helps in collagen formation, boosts immunity, and acts as an antioxidant.

Other options (for context)

• Vitamin-A & Vitamin-B: Vitamin-A is fat-soluble, while Vitamin-B is water-soluble.
• Vitamin-C & Vitamin-D: Vitamin-C is water-soluble, but Vitamin-D is fat-soluble.
• Vitamin-A & Vitamin-K: Both are fat-soluble vitamins.

Explanation: Electromagnetic waves can propagate even through a vacuum because they do not require any material medium for transmission. Examples include light waves, radio waves, X-rays, and microwaves. In contrast, mechanical waves like sound require a medium such as air, water, or solids to travel.

Explanation: In household electrical wiring, all the given statements are correct: the red insulated wire is the live (phase) wire, the black insulated wire is the neutral wire, and the green insulated wire is used for earthing to ensure safety by preventing electric shocks.

The statement “Silver Revolution refers to increased pulse production” is incorrect. The Silver Revolution actually refers to the rapid increase in egg and poultry production in India during the 1980s, which boosted nutrition and rural income.

• White Revolution: Increased milk production under Dr. Verghese Kurien.
• Green Revolution: Rise in food grain output (wheat, rice) using high-yield varieties.
• Yellow Revolution: Boosted oilseed production for self-sufficiency in edible oils.

Explanation: Acupuncture is an ancient form of traditional Chinese medicine that involves the insertion of very thin needles through the skin at specific points, called acupoints. It is based on the concept of balancing the flow of life energy (Qi or Chi) through pathways in the body known as meridians. When these energy flows are blocked or imbalanced, it can cause illness or pain.

By stimulating specific acupoints, acupuncture is believed to restore the normal energy flow and help the body heal itself. It is commonly used to treat:

• Chronic pain (e.g., back, neck, and joint pain)
• Migraines and headaches
• Arthritis and muscle stiffness
• Stress and anxiety

Scientific View: Modern research suggests that acupuncture may stimulate nerves, muscles, and connective tissue, boosting the body’s natural painkillers (endorphins).

Explanation: The rarest blood type in the world is AB⁻ (AB negative). It is found in less than 1% of the global population. People with AB⁻ blood can receive red blood cells from all Rh-negative blood types, but they can donate only to other AB individuals.

Explanation: The main constituents of biogas are methane (CH₄) and carbon dioxide (CO₂). Biogas is produced through the anaerobic decomposition of organic matter such as animal dung and plant waste. Methane acts as the primary combustible component, making biogas an efficient and renewable source of energy.

Deciduous trees are those that shed all their leaves once a year, usually during the dry or winter season to conserve water and energy. After a period of dormancy, they grow new leaves at the beginning of the next growing season. Common examples include teak, sal, neem, and peepal. This adaptation helps the trees survive unfavorable climatic conditions.

Other options (for context)

• Coniferous trees: Mostly evergreen and do not shed all their leaves at once; examples include pine and deodar.
• Evergreen trees: Retain their leaves throughout the year and shed them gradually.
• Both deciduous and coniferous trees: Incorrect — only deciduous trees completely shed their leaves annually.