Question

Give any 2 properties of hydrogen gas and carbondioxide gas.

Answer 1

Carbon dioxide is colorless. At low concentrations the gas is odorless however, at sufficiently-high concentrations, it has a sharp, acidic odor. At standard temperature and pressure, the density of carbon dioxide is around 1.98 kg/m3, about 1.67 times that of air.
At standard temperature and pressure, hydrogen is a nontoxic, nonmetallic, odorless, tasteless, colorless, and highly combustible diatomic gas with the molecular formula H2. Hydrogen is also prevalent on Earth in the form of chemical compounds such as hydrocarbons and water.