Answer : The correct option is, (B) chemical change
Explanation :
Chemical change : It is a change in which a new substance is formed when the changes occurs in the chemical composition. It is usually an irreversible reaction.
Physical change : It is a change in which the shape and the size of a substance changes. There is no change in the composition of the substance. It is usually a reversible reaction.
when potassium chlorate is heated then changes occurs in the chemical composition of the potassium chlorate and the new substance will be formed. So, the chemical change occurs when potassium chlorate is heated.
when potassium chlorate is strongly heated then potassium chloride and oxygen gas is formed.
Hence, the correct option is, (B) chemical change