Which of the following processes is endothermic?

Q. How can a hydrated salt be converted into anhydrous salt?

Q. State the methods by which hydrated salts can be made anhydrous?

Q. A crystalline hydrated salt was heated due to which it gets completely dehydrated and loses $45.6\%$ of its weight. Percentage composition of anhydrous salt is $Al–10.5\%,K–15.1\%,S–24.8\%,O–49.6\%.$ Find molecular formula of salt (hydrated). ($M=948{\text{g mol}}^{-1}$ for hydrated salt).

Q.

What is hydrated and anhydrous salt?