Choose the correct answer for the following assertion and reason questions:
 
1. 
Assertion (A): The explosion of fire cracker is a irreversible change.
Reason (R): The firecracker undergoes a chemical reaction forming a new substance.
 
2. 
Assertion (A): The burning of a candle shows that physical and chemical changes can occur together.
Reason (R):
Melting of wax is a chemical process, whereas burning of wax vapour is a physical process.