Chemistry - Study Mode
[#636] The gas present in the stratosphere which filters out some of the sun's ultraviolet light and provides an effective shield against radiation damage to living things is
Correct Answer
(B) ozone
Explanation
Solution: Although ozone (O3) is present in small concentrations throughout the atmosphere, most ozone (about 90%) exists in the stratosphere, in a layer between 10 and 50 km above the surface of the earth. This ozone layer performs the essential task of filtering out most of the sun's biologically harmful UV radiation.
[#637] The most commonly used bleaching agent is
Correct Answer
(C) chlorine
Explanation
Solution: Most commonly used bleaching agent is chlorine. The most widely used bleach in the United States is liquid chlorine bleach, an alkaline aqueous solution of sodium hypochlorite.
[#638] The nucleus of a hydrogen atom consists of
Correct Answer
(A) 1 proton only
Explanation
Solution: Most hydrogen atoms have nuclei that consist of a single proton, but a small fraction (about 0.015 percent) of the hydrogen atoms that occur in Nature have one neutron in addition to the proton in their nuclei.
[#639] The heat required to raise the temperature of body by 1 K is called
Correct Answer
(B) thermal capacity
Explanation
Solution: The heat required to raise the temperature of a body by 1 K is called thermal capacity. In other words, when q is the heat supplied to the body and the temperature raises by 1 K, then the thermal capacity of body is q.
[#640] The nuclear particles which are assumed to hold the nucleons together are
Correct Answer
(D) mesons
Explanation
Solution: Nuclear particles responsible for holding all nucleons together are mesons. To account for the binding forces between like particles such as proton and proton or neutron and neutron, Kemmer suggested the existence of a neutral meson (π0).