Write are four uses of dihydrogen(`H_2`).

Write any four uses of aluminium.

Write any four uses of CO_2 gas.

Write any four uses of sodium metal.

Write any four uses of washing soda.

Give four uses of emulsions.

Write any four uses of metals in different situations.

Give four uses of heavy water.

Write four reducing properties of hydrogen peroxide.

A mixture of dihydrogen and dioxygen at one bar pressure contains 20% by weight of dihydrogen. Calculate the partial pressure of dihydrogen.