Explanation: An artery is a large blood vessel that carries blood away from the heart to various parts of the body. Arteries have thick, elastic walls to withstand high pressure. In contrast, veins carry blood toward the heart, and capillaries are tiny vessels that connect arteries and veins.

Explanation: The Bureau of Energy Efficiency (BEE) is an autonomous government agency set up by the Government of India under the Ministry of Power in 2002. It was established under the provisions of the Energy Conservation Act, 2001. The primary objective of BEE is to promote policies and programs that increase the efficiency of energy use in various sectors of the economy. BEE also develops energy efficiency standards and labeling programs for appliances and buildings, such as the star-rating system seen on electrical devices.

The physical quantity measured in kg·m/s² is Force. The SI unit of force is the Newton (N), which is defined as the force required to accelerate a mass of 1 kilogram by 1 meter per second squared. Mathematically, Force = Mass × Acceleration.

• Work: Measured in joules (N·m).
• Power: Measured in watts (J/s).
• Motion: Describes movement, not a measurable quantity in these units.

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.

Metals can be beaten into thin sheets because they are malleable. Malleability is a physical property of metals that allows them to withstand hammering or rolling without breaking. This property is due to the metallic bonding where positive metal ions are surrounded by a ‘sea’ of delocalized electrons, allowing the layers of atoms to slide over each other without breaking the bond. Examples of highly malleable metals include gold, silver, and aluminium.

Other options (for context)

• Ductile: Refers to the ability of metals to be drawn into wires, not beaten into sheets.
• Soft: Not true for all metals — many are hard yet malleable.
• Loosely arranged particles: Incorrect — metal atoms are closely packed in a lattice structure.

Explanation: The processes that add carbon dioxide (CO₂) to the carbon cycle on Earth are:

• 1. Volcanic action: Volcanic eruptions release large amounts of CO₂ and other gases from the Earth’s interior into the atmosphere.
• 2. Respiration: All living organisms release CO₂ as a by-product of breaking down glucose during cellular respiration.
• 4. Decay of organic matter: Decomposition of dead plants and animals by microbes produces CO₂ and methane (CH₄).

Photosynthesis (option 3), on the other hand, removes CO₂ from the atmosphere as plants use it to produce glucose and release oxygen.

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.

Explanation: Sound waves with frequencies below 20 Hz are called infrasonic waves. These waves are inaudible to the human ear but can be produced by natural phenomena such as earthquakes, volcanic eruptions, and ocean waves.

Explanation: The gastric glands in the stomach secrete gastric juice, which contains three main components — hydrochloric acid (HCl), pepsinogen, and mucus. Pepsinogen is the inactive form that is converted to pepsin by HCl. Pepsin is a powerful enzyme that digests proteins into smaller peptides in the acidic environment of the stomach.