Explanation: The weight of a person depends on the gravitational force exerted by a celestial body. The Moon’s gravity is only about 1/6th that of the Earth’s because it has much less mass and a smaller radius. Therefore, an object or person weighing 60 kg on Earth would weigh only about 10 kg on the Moon. Although mass remains constant everywhere, weight changes according to the local gravitational acceleration (g). Hence, lower gravity results in lower weight on the Moon.

Explanation: Mumps is a contagious viral disease caused by the mumps virus, a member of the Paramyxoviridae family (genus Rubulavirus). It primarily affects the salivary glands, especially the parotid glands, leading to painful swelling near the cheeks and jawline.

Mode of Transmission: The infection spreads through respiratory droplets or direct contact with saliva from an infected person.

Symptoms:

• Swelling and pain in the parotid glands (below the ears)
• Fever and headache
• Muscle pain and fatigue
• Difficulty in chewing or swallowing

Prevention: Mumps can be effectively prevented by the MMR vaccine (Measles, Mumps, and Rubella vaccine).

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: Liquid Natural Gas (LNG) predominantly contains methane (CH₄) in liquid form. It is produced by cooling natural gas to about −162°C, which reduces its volume for easier storage and transportation. LNG is a clean fuel with high energy efficiency and low emissions.

Explanation: Internet is the odd one out because it is a global network, whereas Linux, Unix and Windows are operating systems.

Explanation: Fibrinogen is a soluble plasma protein produced by the liver. During blood clotting, it is converted into insoluble fibrin threads by the enzyme thrombin. These fibrin threads form a mesh that traps red blood cells and platelets, creating a stable clot to stop bleeding. This process prevents excessive blood loss during injury and is regulated by clotting factors and platelets.

Simplified Reaction:

Fibrinogen → (Thrombin) → Fibrin → Blood Clot

Explanation: Normal human blood has a slightly alkaline pH of 7.35 to 7.45. This pH is maintained by buffer systems such as the bicarbonate buffer system and controlled by the lungs (CO₂ regulation) and kidneys (acid-base balance). A deviation from this range can be life-threatening — acidosis occurs if pH falls below 7.35, and alkalosis occurs if it rises above 7.45.

Sound becomes hazardous and causes noise pollution when its intensity exceeds 80 decibels (dB). Prolonged exposure to such high noise levels can lead to hearing loss, stress, sleep disturbances, and other health problems. Common sources include heavy traffic, loudspeakers, machinery, and construction activities. Sounds above 120 dB can cause immediate ear damage or pain.

Other options (for context)

• Above 50 dB: Considered moderate — typical of normal conversation or office noise.
• Above 100 dB: Very loud and potentially painful, but 80 dB is the threshold for long-term hazard.
• Above 130 dB: Extremely loud, causes immediate physical pain and ear damage.

Explanation: The gas used for artificial ripening of green fruits is ethylene (C₂H₄). Ethylene is a natural plant hormone that regulates fruit ripening by stimulating the conversion of starches into sugars, making the fruit softer and sweeter. In artificial ripening, ethylene gas is introduced in controlled amounts to uniformly ripen fruits such as bananas, mangoes, and tomatoes. However, the use of harmful chemicals like calcium carbide for ripening is banned because it produces toxic substances like acetylene.