Chemistry of Gases and Applications

Acetylene (C2H2) is an alkyne with a triple bond. It decolorizes alkaline KMnO4 due to unsaturation and forms a white precipitate of silver acetylide with ammoniacal AgNO3. Methane (C2H6 is ethane, C2H4 is ethene, C2H is not a stable hydrocarbon) do not give both reactions.

1. Solid carbon dioxide is commonly called as dry ice.
   1. Nitrous oxide (N₂O) has been used for anesthesia in dentistry and other surgical operations. Solid carbon dioxide is commonly called as dry ice. 3. On heating NH₄Cl, it goes to gaseous state due to the process of sublimation. A change of state directly from solid to gas without changing into liquid state is called sublimation.

P. Nitrous oxide (N₂O) is commonly known as laughing gas. Q. On Kelvin scale, 0^oC is equal to - 273 K. R. Carbon dioxide is used to produce carbonated soft drinks and soda water.

CFC - Chlorofluorocarbons

Sulphur dioxide gas was used in refrigerator as refrigerant in previous years. Halogenated hydrocarbons are frequently used as refrigerant in refrigerator. Methyl chloride is used in refrigerator as refrigerant. A chlorofluorocarbon (CFC) is an organic compound that contains only carbon, chlorine, and fluorine, produced as a volatile derivative of methane, ethane, and propane. They are also commonly known by the DuPont brand name Freon. The most common representative is dichlorodifluoromethane (R-12 or Freon-12). Many CFCs have been widely used as refrigerants, propellants (in aerosol applications), and solvents.

Freon (chlorofluorocarbon or CFC) was the most widely used refrigerant in domestic refrigerators and cold storage facilities for decades due to its excellent thermodynamic properties. Neon is a noble gas used in lighting, while crypton (likely a misspelling of krypton) is another noble gas. Freon has been largely phased out due to ozone depletion concerns, but it was the standard refrigerant when this question was framed.

This is the correct option. Oxygen is formed at the anode, which is connected to the positive terminal of the battery when electric current is passed through acidified water.

Air is a mixture of various gases. The main gases present in air are nitrogen (78.1% by volume) and oxygen (20.9% by volume). These two gases together form 99% of the air. Besides these two, air contains small amounts of carbon dioxide (0.03 to 0.04%), water vapour (variable), noble gases (0.94%), and dust particles.

Oxygen present in air reacts wiyh nitric oxide results of form reddish brown gas.

Carbondioxide turns lime water milky.

The main gas present in the air is nitrogen (78.1% by volume) and it helps in diluting the effect of oxygen. The noble gases present in the air are helium, neon, argon, krypton and xenon. Since the percentage of these gases is very small, so, these gases are also called "rare gases".

Nitrogen > oxygen > argon > carbon dioxide > other gases is the correct answer.

It contains only mercury atoms (Hg).

Carbon dioxide gas is heavier than oxygen, so it creates a blanket around the burning fuel and displaces the oxygen surrounding the fuel. In a carbon dioxide extinguisher, the carbon dioxide is kept in pressurised liquid form in the cylinder. When the container is opened, the carbon dioxide expands to form a gas in the atmosphere or to simplify, it removes oxygen from the fire triangle, to smother it and extinguish it.

Hydrogen gas has the highest calorific value among all fuels at approximately 142 kJ/g, significantly higher than methane (~55 kJ/g), ethane (~52 kJ/g), or biogas (~20-25 kJ/g). Option B correctly identifies hydrogen as having the highest calorific value. Option A (methane) has a high calorific value but not the highest. Options C and D have lower calorific values compared to hydrogen.