Chemistry - Study Mode

[#881] Oxygen which is vital for life is a product of photosynthesis and comes from
Correct Answer

(C) Water

Explanation

Solution: The unusually high concentration of oxygen gas on Earth is the result of the oxygen cycle. This biogeochemical cycle describes the movement of oxygen within and between its three main reservoirs on Earth: the atmosphere, the biosphere, and the lithosphere. The main driving factor of the oxygen cycle is photosynthesis, which is responsible for modern Earth’s atmosphere. Photosynthesis releases oxygen into the atmosphere, while respiration and decay remove it from the atmosphere. In the present equilibrium, production and consumption occur at the same rate of roughly 1/2000th of the entire atmospheric oxygen per year. Free oxygen also occurs in solution in the world’s water bodies. The increased solubility of O 2 at lower temperatures has important implications for ocean life, as polar oceans support a much higher density of life due to their higher oxygen content.

[#882] Which one of the following is a greenhouse gas ?
Correct Answer

(C) Carbon dioxide

Explanation

Solution: Carbon dioxide is a greenhouse gas.

[#883] Acid rain is caused by the pollution of environment by
Correct Answer

(C) Nitrous oxide and Sulphur dioxide

Explanation

Solution: Acid rain is caused by a chemical reaction that begins when compounds like sulphur dioxide and nitrogen oxides are released into the air. These substances can rise very high into the atmosphere, where they mix and react with water, oxygen, and other chemicals to form more acidic pollutants, known as acid rain.

[#884] The ‘Green House effect’ is produced due to the presence of excess amount of
Correct Answer

(D) Methane

Explanation

Solution: By their percentage contribution to the greenhouse effect on Earth the four major gases are: Water vapour (36-70%), Carbon dioxide (9-26%), Methane (4-9%) and Ozone (3-7%).

[#885] Which gas does not form the part of atmosphere ?
Correct Answer

(C) Chlorine

Explanation

Solution: The atmosphere of Earth is a layer of gases surrounding the planet Earth that is retained by Earth’s gravity. The atmosphere protects life on Earth by absorbing ultraviolet solar radiation, warming the surface through heat retention (greenhouse effect), and reducing temperature extremes between day and night (the diurnal temperature variations). Air is the name given to the atmosphere used in breathing and photosynthesis. Dry air contains roughly (by volume) 78.09% nitrogen, 20.95% oxygen, 0.93% argon, 0.039% carbon dioxide, and small amounts of other gases. Air also contains a variable amount of water vapor, on average around 1%. While air content and atmospheric pressure vary at different layers, air suitable for the survival of terrestrial plants and terrestrial animals is currently only known to be found in Earth’s troposphere and artificial atmospheres. Air is mainly composed of nitrogen, oxygen, and argon, which together constitute the major gases of the atmosphere. The remaining gases are often referred to as trace gases, among which are the greenhouse gases such as water vapour, carbon dioxide, methane, nitrous oxide, and ozone. Filtered air includes trace amounts of many other chemical compounds.