Chemistry of Gases and Applications

 Hydrogen and helium, the lightest two gases, weigh so little that helium balloons and hydrogen dirigibles are able to float in the atmosphere.

Hydrogen is used in the hydrogenation of vegetable oils to make vegetable ghee. 

Nitrogen is filled in bulbs. Argon is another noble gas and is used to keep light bulb filaments from burning away. Since argon is non-reactive, it is filled in a light bulb instead of regular air, which contains oxygen that can cause a burning reaction when exposed to the thin metal filaments found in light bulbs. Other noble gases include krypton, xenon and radon.

Helium is an element. Other options are compounds.

A mixture is a material, which consists of two or more pure substances (elements or compounds) which are not chemically combined but physically mixed in any proportion. A mixture shows the properties of all its constituents and it can be reported into its constituents by physical method. Air is a homogeneous mixture of many gases like nitrogen (78%), oxygen (21%), carbon dioxide, inert gases and water vapours. Air is a mixture because its properties are in between those of its constituents. The two major components of air are oxygen and nitrogen. In the presence of oxygen, any fuel burns brightly but in nitrogen it gets extinguished. In contrast, in air, the fuel burns slowly. The components of air can be separated by fractional distillation; moreover the composition of air is also variable. Thus, air is a mixture. An element is a pure substance that contains only one kind of atoms. A molecule is a group of two or more atoms, which are held together strongly by some kind of attractive force. For e.g. H₂, Cl₂, Br₂, etc. A compound is made up of two or more elements chemically combined in fixed proportion by mass. For e.g. H₂O, HCl, NH₃, etc.

In ammonia, the ratio of elements is always fixed. This is because ammonia is a compound.

Before life, Earth's atmosphere had ammonia, methane, and free hydrogen, but no free oxygen. Free oxygen only appeared after photosynthetic organisms evolved and started producing it as a byproduct.

Yeast is the organism, which is added to the dairy products to increase their volume. When the yeast cells multiply, they breathe and release carbon dioxide, which causes an increase in the volume of food products. 

The gas which leaked from the Union Carbide Plant in Bhopal in 1984 was methyl isocyanate. 

Life cannot currently originate from inorganic compounds because high oxygen levels oxidize and break down organic molecules before they can form complex life. Early Earth had little oxygen, allowing organic molecules to accumulate. The other options are incorrect - hydrogen is still available, raw materials exist, and temperature is suitable.

Correct answer. Among the given options, ammonia has the highest solubility in water. 

Carbon dioxide is the best extinguishing agent for electrical fires and flammable liquid fires like petrol because: (1) It is non-conductive, so it won't cause electric shocks, (2) It is heavier than air and forms a blanket over the fire, cutting off oxygen supply, and (3) It doesn't leave residue or damage electronic equipment. Oxygen would fuel the fire, nitrogen is less effective, and hydrogen is highly flammable.

 Oxygen is an essential gas for combustion.

The rare gas which is present most abundantly in air is argon.

Group 18 elements are known as inert elements. For example, helium, neon, argon, krypton, etc.