Write the symbols of the following elements: 

Iron, gold, lead, mercury, sodium, potassium. 

Write the chemical formula of Magnesium oxide. 

Write the chemical formulae of calcium carbonate. 

Define atomicity. Explain the different types of atomicity with examples. 

Identify the constituent elements in the following compounds: 

Calcium oxide, ammonia, nitric acid, calcium carbonate, copper sulphate. 

Write the formulae of the following compounds:

Nitric acid, hydrogen gas, carbonic acid, hydrogen chloride gas, copper sulphate, ammonium hydroxide.

Identify the different types of mixtures:

Aerated water, oil and water, sand and water, smoke, bronze, gun powder.