Question

Which one of the following is a chemical change?Give two reason also
(a) burning of wax
(b) melting of wax

Answer 1

Answer:

Burning of wax is a chemical change.

Explanation

There are 2 types of changes - Physical and chemical.

PHYSICAL CHANGE - It's a change in a substance just in it's physical state. Thus no new substance is formed. Here melting of wax is a physical change as there is no new substance formed here. There was solid wax which is just melted now. Only the state has changed and nothing new is produced here. Also such changes are reversible.

CHEMICAL CHANGE - In such changes a new substance is formed. Thus it involves breaking of old bonds and formation of new ones. Here burning of wax is a chemical change as now the wax is turned into ashes and carbon dioxide is also released. Thus new substance is formed which makes it a chemical change. Rusting of iron is another example. Also not these changes are irreversible in nature.

Answer 2

Burning of gas is a chemical change because new products with new properties will be formed on burning.