Ozone depletion is greatest near
- A.tropics
- B.equator
- C.poles
- D.oceans
Correct answer
Explanation
The correct answer is C, the poles. Chlorine released from chlorofluorocarbons destroys ozone fastest where polar stratospheric clouds form in the extreme cold of winter, because those ice clouds hold the chlorine compounds that sunlight then breaks up; the thinning is therefore deepest over Antarctica, where it is called the ozone hole, and is seen over the Arctic as well. Option A, the tropics, is wrong because ozone is actually produced there in the greatest quantity, as the sunlight is strongest over the equatorial belt. Option B, the equator, is wrong for the same reason, and the ozone made there is carried polewards by stratospheric circulation. Option D, the oceans, is wrong because ozone loss is a matter of latitude and temperature in the stratosphere and not of the surface below. The Montreal Protocol of 1987 was agreed to phase out such substances.
Read the full article: Important Gases and Their Uses: Notes and PYQs
Practice Questions
View allWhich gas is typically produced when a metal reacts with an acid?
- A.Carbon dioxide
- B.Oxygen
- C.Hydrogen
- D.Nitrogen
Show answer
A metal more reactive than hydrogen displaces it from a dilute acid, so zinc with dilute sulphuric acid gives zinc sulphate and hydrogen gas, and this is the standard laboratory preparation of the gas; the test is that it burns with a pop.
Read the full explanation →Which of the following is a radioisotope of hydrogen?
- A.Xenon
- B.Technetium
- C.Thorium
- D.Tritium
Show answer
Hydrogen has three isotopes: protium with one proton and no neutron, deuterium with one neutron, which gives heavy water, and tritium with two neutrons, which is radioactive and is used in fusion research and in luminous dials.
Read the full explanation →Which gas is commonly known as laughing gas?
- A.Nitric oxide
- B.Nitrogen dioxide
- C.Nitrous oxide
- D.Ammonia
Show answer
It is called laughing gas because it produces a feeling of elation when inhaled in small quantities, and it is used as a mild anaesthetic in dentistry and minor surgery and as the propellant in whipped cream; it is also a greenhouse gas.
Read the full explanation →Which gas is filled in electric bulbs so that the filament lasts longer?
- A.Oxygen
- B.Argon
- C.Chlorine
- D.Carbon dioxide
Show answer
Argon is chemically inert, so the hot tungsten filament does not react with it, and its presence also slows the evaporation of tungsten, which is why bulbs are filled with argon, sometimes mixed with nitrogen, instead of being left as a vacuum.
Read the full explanation →Which gas is used in advertising signs and gives a reddish-orange glow in a discharge tube?
- A.Helium
- B.Neon
- C.Krypton
- D.Radon
Show answer
When an electric discharge is passed through neon at low pressure it glows a bright reddish orange, which is why the tubes of advertising signs and warning lights are filled with it, and the name neon sign has stuck to such tubes whatever gas they now contain.
Read the full explanation →