Chemistry of Gases and Applications

Nitrogen dioxide (NO2) is used as an antichlor in bleaching and textile processes because it acts as a reducing agent to neutralize excess chlorine. Hydrogen sulfide and sulfur dioxide are also reducing agents but are not typically called antichlors. Ammonium nitrate is an oxidizer, not an antichlor.

Nitrogen makes up approximately 78% of Earth's atmosphere by volume, making it the most abundant gas. Oxygen is the second most abundant at about 21%, while hydrogen and carbon dioxide exist only in trace amounts (less than 1%).

Carbon dioxide (CO2) has a molecular weight of 44 g/mol, making it the heaviest among common atmospheric gases when comparing molecular masses. At standard temperature and pressure, CO2 is about 1.5 times denser than air. Argon is actually heavier (40 g/mol) than CO2, but among the given choices and in the context of common atmospheric gases students learn, CO2 is typically taught as the heaviest common gas.

Plants release carbon dioxide during respiration as they metabolize glucose for energy through cellular respiration. This process consumes oxygen and produces CO2 as a metabolic byproduct.

The Bhopal gas tragedy of 1984 was caused by methyl isocyanate (CH3NCO or MIC), a highly toxic chemical used in pesticide production. The gas leak from Union Carbide plant released this compound, which caused thousands of deaths and injuries due to its extreme toxicity to respiratory systems.

Nitrous oxide (N2O) is commonly known as laughing gas due to its euphoric effects when inhaled. It's used in medicine and dentistry for its anesthetic and analgesic properties.

Dihydrogen monoxide literally means 'two hydrogen, one oxygen' (H2O), which is water. This technical name is often used humorously to make water sound dangerous, but it's simply the systematic chemical name.

Nitrous oxide (N2O) is commonly called 'laughing gas' because it induces euphoria and laughter when inhaled. It's used as an anesthetic and analgesic in medical and dental procedures. The other options (alcohol, helium gas, sugar) are different substances entirely.

Trinitrotoluene is a yellow solid explosive compound commonly abbreviated as TNT. It's widely used in military and industrial applications. Nitro-glycerine and dynamite are related explosives, while gun powder is a different explosive mixture.

Nitrous oxide (N2O), commonly known as laughing gas, is a colorless, sweet-tasting gas used as an anesthetic and analgesic in dentistry and medicine. It was discovered in 1772 by Joseph Priestley and named 'laughing gas' due to the euphoric effects it produces when inhaled.

Brass (an alloy of copper and zinc) discolours in air due to reaction with hydrogen sulphide, forming a dark layer of copper sulphide on the surface. Oxygen, carbon dioxide, and nitrogen do not cause this discolouration. This is a common chemistry phenomenon observed in brass objects.

Nitrogen gas is filled in electric bulbs because it is inert and prevents the filament from oxidizing at high temperatures. Hydrogen is reactive and would damage the filament. Oxygen would cause burning and carbon dioxide is not used for this purpose.

Helium is used in diving gas mixtures (like Heliox) because it's inert and reduces nitrogen narcosis risk at depth. Unlike nitrogen, helium doesn't dissolve into tissues as readily, decreasing decompression sickness risk.

Oxy-acetylene welding uses oxygen and acetylene to create an extremely hot flame (~3200°C) suitable for welding and cutting metals. Acetylene provides the fuel, while oxygen supports complete combustion.

Ethyl mercaptan (ethanethiol, C2H5SH) is a sulfur-containing organic compound added to odorless LPG in trace amounts. The sulfur atoms give it the extremely strong, unpleasant smell that alerts users to gas leaks.