Write the balanced chemical equations of the following reactions.

copper + nitric acid → copper nitrate + nitric oxide + water

Name the fundamental law that is involved in every equation.

What is the valency of :

fluorine in CaF₂ 

What is the valency of :

sulphur in SF₆

What is the valency of :

phosphorus in PH₃ 

What is the valency of :

carbon in CH₄

What is the valency of :

nitrogen in the following compounds:

(i) N₂O₃ (ii) N₂O₅ (iii) NO₂ (iv) NO

Why should an equation be balanced? Explain with the help of a simple equation.

Write the balanced chemical equations of the following reactions. sodium hydroxide + sulphuric acid → sodium sulphate + water

Write the balanced chemical equations of the following reactions. potassium bicarbonate + sulphuric acid → potassium sulphate + carbon dioxide + water

Write the balanced chemical equations of the following reactions. iron + sulphuric acid → ferrous sulphate + hydrogen.