Who discovered the electron?

$2Na_{(s)} + 2H_2O_{(l)} \longrightarrow ?$

$A$ metal compound $'A'$ reacts with dilute sulphuric acid to produce a gas which extinguishes a burning candle. Identify the compound $'A'$ and the gas produced. Write a balanced chemical equation for the reaction if one of the compounds formed in the reaction is sodium sulphate.

$NH_{3}$ is used in the preparation of nitric acid by $.....$ process.

What is the difference between displacement and double displacement reactions? Write equations for these reactions.

In the presence of which catalyst is sulphur dioxide heated at high temperature to form sulphur trioxide?