Correct Answer – (1) nuclear fusion
Explanation: The central mass of the sun becomes increasingly hot and dense. eventually initiating thermonuclear fusion in its core. It is thought that almost all other stars form by this process, nuclcar fusion is a nuclcar reaction in which two or more atomic nuclei join together, or “fuse”, to form a single heavier nucleus. During this process, matter is not conserved because some of the mass of the fusing nuclei is converted to energy which is released.

Correct Answer – (3) Anthracite
Explanation: The heat content of anthracite ranges from 22 to 28 million Btu per short ton (26 to 33 MJ/kg) on a moist, mineral-matter-free basis. Anthracite (“coal-like”) is a hard, compact variety of mineral coal that has a high luster. It has the highest carbon content, the fewest impurities, and the highest calorific content of all types of coals, which also include bituminous coal and lignite.

Correct Answer – (1) has high specific heat
Explanation: The specific heat of water is higher than all other common substances. Hence, water is used for heating purposes (as in hot water bottles) and for cooling purposes (as in radiators of cars). Off all the liquids, mercury has the lowest specific heat due to which it is used as a thermometric liquid.

Correct Answer – (1) equal volume
Explanation: When a body is placed in water, the upthrust or buoyant force acting on it depends upon the following factors: (1) Volume of the body submerged in the liquid (V), or volume of the liquid displaced – (V); (t) Density of the liquid – (d); and (Hi) Acceleration due to gravity In-linc.

Distamce
Explanation: A light-ycar is a unit of length equal to just under 10 trillion kilometres (or about 6 trillion miles). As defined by the International Astronomical Union (TAU), a light-year is the distance that light travels in a vacuum in one Julian year. Note that the licht- year is a measure of distance (rather than, as is sometimes misunderstood, a measure of time).