Assertion (A): The changes which result in the formation of new substances with entirely different composition and properties are called chemical changes.

Reason (R): Chemical changes are permanent and irreversible.

1. Both A and R are true and R is the correct explanation of A.
2. Both A and R are true but R is not the correct explanation of A.
3. A is true but R is false
4. A is false but R is true.

Assertion (A): When a change in a substance can be reversed by changing the conditions, it is said to be a reversible and temporary change.

Reason (R): Burning a piece of paper is a reversible change.

1. Both A and R are true and R is the correct explanation of A.
2. Both A and R are true but R is not the correct explanation of A.
3. A is true but R is false
4. A is false but R is true.

Assertion (A): For rust formation to take place, iron must be exposed to air and water for some time.

Reason (R): Rust is a reddish brown substance formed on the surface of iron.

1. Both A and R are true and R is the correct explanation of A.
2. Both A and R are true but R is not the correct explanation of A.
3. A is true but R is false
4. A is false but R is true.

Assertion (A): Burning of a candle is a physical change.

Reason (R): When a candle burns, some of its wax melts and gets solidified on cooling. Also carbon dioxide and water vapour are formed which cannot be recovered easily and converted back into the candle.

1. Both A and R are true and R is the correct explanation of A.
2. Both A and R are true but R is not the correct explanation of A.
3. A is true but R is false
4. A is false but R is true.