Which gas is filled in electric bulbs so that the filament lasts longer?
- A.Oxygen
- B.Argon
- C.Chlorine
- D.Carbon dioxide
Correct answer
Explanation
The correct answer is B, argon. 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. Option A, oxygen, is wrong because oxygen supports combustion and would burn the filament away at once. Option C, chlorine, is wrong because chlorine is reactive and corrosive and would attack the metal. Option D, carbon dioxide, is wrong because it is not used for this purpose, although it does not support burning; it serves instead in fire extinguishers and aerated drinks. Argon is the commonest noble gas in the atmosphere, at about 0.93 per cent by volume, and is also used as a shielding gas in arc welding.
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
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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
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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 →Ozone depletion is greatest near
- A.tropics
- B.equator
- C.poles
- D.oceans
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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…
Read the full explanation →Which gas is commonly known as laughing gas?
- A.Nitric oxide
- B.Nitrogen dioxide
- C.Nitrous oxide
- D.Ammonia
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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 used in advertising signs and gives a reddish-orange glow in a discharge tube?
- A.Helium
- B.Neon
- C.Krypton
- D.Radon
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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.
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