What are Rubies and Sapphires chemically known as?

In which one of the following cases do both physical and chemical changes take place?

Which one of the following is a chemical change?

Which one among the following is an example of chemical change?

Which of the following is the example of chemical change?

Which of the following is/are the example/examples of chemical change? 1. Crystallization of sodium chloride 2. Melting of ice 3. Souring of milk Select the correct answer using the code given below.