Chemistry of Gases and Applications

Sulphur dioxide (SO2) acts as an acidic gas only in the presence of moisture, where it forms sulphurous acid. Dry litmus paper lacks the water necessary for this reaction, so it remains unaffected.

Mustard gas was one of the most infamous chemical weapons used during the First World War, causing severe skin and respiratory damage.

Methane (CH4) is the primary component of natural gas, typically accounting for 70 to 90 percent of its composition.

Gobar gas, or biogas, is produced by the anaerobic digestion of organic matter and consists primarily of methane (50-75%) and carbon dioxide.

Compressed Natural Gas (CNG) is primarily composed of methane, with smaller amounts of ethane and other hydrocarbons.

Water gas is a synthesis gas produced from steam and carbonaceous material, consisting primarily of carbon monoxide and hydrogen.

This is the correct option. Carbon dioxide gas is used to extinguish electric fires.

Dry ice is the solid form of carbon dioxide. It is produced by compressing and cooling gaseous carbon dioxide until it undergoes a phase change into a solid.

Nitrogen makes up about 78 percent of the Earth's atmosphere and is relatively inert. Its presence dilutes oxygen, which prevents combustion from occurring too rapidly or uncontrollably.

Carbon dioxide is denser than air and does not support combustion, making it effective for extinguishing fires.

This option is correct because a fraction of middle oil contains mainly phenol. Naphthalene crystallises out upon cooling. It is purified by sublimation and used for the manufactured of dyes, drugs, etc.

The Earth's atmosphere is composed of approximately 78 percent nitrogen, 21 percent oxygen, and about 0.93 percent argon. Argon is the third most abundant gas.

Nitrogen is produced in the laboratory by heating ammonium chloride (NH4Cl) with sodium nitrite (NaNO2), producing NaCl, N2, and H2O. This is a standard nitrogen preparation method. Option B has a typo (nitrarte), and options C and D don't produce nitrogen gas.

Carbon dioxide is highly soluble in water, especially under pressure, forming carbonic acid. Oxygen and nitrogen have much lower solubility in water.

Hydrogen is the lightest element in the periodic table, with an atomic mass of approximately 1.008. Because it exists as a diatomic gas (H2), it remains the lightest gas compared to nitrogen or ammonia.