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.

Sputnik I was the first artificial satellite to orbit the Earth. It was launched by the Soviet Union on October 4, 1957. The successful launch of Sputnik I marked the beginning of the space age and initiated the space race between the USA and the USSR.

• Explorer I: First U.S. satellite, launched in 1958.
• Vanguard I: A U.S. satellite launched later in 1958.
• Discoverer I: Part of an American reconnaissance satellite program (1959).

Explanation: The heart is enclosed in a double-layered protective membrane called the pericardium. The outer fibrous layer protects the heart and anchors it within the chest cavity, while the inner serous layer secretes pericardial fluid that reduces friction during heartbeats. This fluid-filled sac ensures smooth and cushioned movement of the heart as it contracts and relaxes continuously.

In medical terminology, USG stands for Ultrasonography. It is a diagnostic imaging technique that uses high-frequency sound waves to create images of internal organs, tissues, and developing fetuses. USG is commonly used in obstetrics, cardiology, and abdominal examinations as it is safe and non-invasive.

• Undersized gland: Not a recognized medical term.
• Unsegmented gonads: Incorrect and unrelated to imaging.
• None of the above: Incorrect as option B is correct.

India’s first successful atomic device was tested at Pokhran in the Thar Desert of Rajasthan on 18th May 1974. The operation was code-named "Smiling Buddha" and was conducted by the Bhabha Atomic Research Centre (BARC) under the leadership of scientists like Dr. Raja Ramanna. This event marked India’s entry into the group of nuclear-capable nations.

Other options (for context)

• Bikaner: A city in Rajasthan, but no nuclear tests were conducted there.
• Barmer: Located near the Pakistan border, not the site of India’s nuclear test.
• Jaisalmer: Close to Pokhran geographically, but not the test location.

The pale yellow colour of urine is due to the presence of the pigment Urochrome. Urochrome is a waste product formed from the breakdown of hemoglobin in red blood cells. It is produced when hemoglobin is metabolized into urobilin and then excreted through urine. The intensity of the yellow color can vary depending on hydration levels — darker urine indicates dehydration, while pale urine indicates proper hydration.

Other options (for context)

• Urophyll: No such pigment exists in human physiology.
• Chlorophyll: Green pigment found in plants, not in urine.
• Chloroplast: Cell organelle in plants where photosynthesis occurs, not a pigment.

Explanation: ROM (Read Only Memory) retains its data even when the power is turned off, making it non-volatile memory. It stores essential programs such as the computer’s firmware or BIOS, which are required for booting the system. In contrast, RAM loses all information when power is shut down.

Explanation: VoIP (Voice over Internet Protocol) is a technology that allows users to make telephone calls over the Internet instead of traditional telephone lines. It converts voice signals into digital data packets and transmits them through computer networks, enabling cost-effective communication worldwide.

Explanation: The troposphere is the lowest layer of the Earth's atmosphere and is closest to the Earth's surface. It extends up to about 8–15 km from the surface, depending on latitude and season. This layer contains about 75% of the total atmospheric mass and almost all the water vapor and weather phenomena such as clouds, rain, and storms occur here. The temperature decreases with increasing altitude in this layer. The boundary between the troposphere and the stratosphere is known as the tropopause.

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.