Nitrous oxide (N₂O) is an anaesthetic gas, commonly known as laughing gas. It is used in dentistry and minor surgeries to induce mild anesthesia and relaxation. It acts quickly and wears off rapidly, making it safe for short medical procedures.

• Nitrogen dioxide: A toxic air pollutant, not used as anesthesia.
• Nitric oxide: A signaling molecule in the body, not an anesthetic.
• Nitrogen: An inert gas, does not induce anesthesia.

Explanation: An F1 (Formula One) car is primarily made of carbon fibre, a lightweight yet extremely strong and durable material. Carbon fibre provides high strength-to-weight ratio, excellent rigidity, and improved safety — essential for achieving high speeds and ensuring driver protection in racing conditions.

Explanation: A strong-smelling compound called thioethanolamine (or ethyl mercaptan) is added to LPG (liquefied petroleum gas) to help detect gas leaks. LPG itself is odourless, so this compound gives it a distinct unpleasant smell, making leakage easily noticeable for safety.

Explanation: A rainbow is formed in the part of the sky opposite to the Sun. It occurs when sunlight is refracted, internally reflected, and dispersed by raindrops, splitting the light into its seven constituent colors. The observer must have the Sun behind them and rain in front to see the rainbow clearly.

Explanation: The incorrect pair is Faraday : Diffusion of gases. The diffusion of gases was studied and explained by Thomas Graham, not by Michael Faraday. Graham’s Law states that the rate of diffusion of a gas is inversely proportional to the square root of its density or molar mass. On the other hand, Michael Faraday is famous for his work on electromagnetism and electrolysis. The other pairs are correctly matched with their discoveries.

Anaemia is caused due to a deficiency of iron in the body. Iron is an essential component of hemoglobin, the protein in red blood cells that carries oxygen. When the body lacks sufficient iron, it produces fewer and smaller red blood cells, leading to symptoms such as fatigue, weakness, dizziness, and pale skin. This condition is known as Iron-Deficiency Anaemia.

Other options (for context)

• Iodine: Its deficiency causes goitre, not anaemia.
• Vitamin: Certain vitamins like B₁₂ and folic acid deficiency can cause anaemia, but the most common cause is lack of iron.
• None of these: Incorrect — iron deficiency is the main cause of anaemia.

Explanation: Sound travels fastest in steel because it is a solid material where the particles are packed very closely together. Sound waves need a medium to travel, and their speed depends on how quickly vibrations can pass from one particle to another. In solids, particles are tightly bound, so vibrations are transmitted more efficiently. In contrast, sound travels slower in liquids and slowest in gases. It cannot travel through a vacuum because there are no particles to carry the vibrations.

Explanation: Lysosomes are known as the ‘suicidal bags’ or ‘disposal units’ of the cell because they contain powerful digestive enzymes capable of breaking down worn-out cell parts, foreign substances, and even the entire cell when it becomes damaged or obsolete.

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.

Explanation: A parity bit is added to binary data in a computer system for error detection. It helps identify whether data has been altered during transmission or storage. The parity bit makes the total number of 1s either even (even parity) or odd (odd parity), allowing simple error checking.