(b) Sodium sulphate
Sodium sulphate is not a chemical fertilizers.
Chemical fertilizers are chemical substances which are used as nutrient supplements to increase the yield of crops.
It is produced in factories while natural fertilizers are produced in the natural environment by decomposition of organic wastes.
There are four types of chemical fertilizers:
Nitrate fertilizers such as sodium nitrate, potassium nitrate, etc.
Ammonium fertilizers such as ammonium sulphate, ammonium phosphate, etc.
Nitrate and ammonium fertilizers such as ammonium sulphate.
Amide fertilizers such as urea, ammonium chloride, etc.