Fill in the blanks from the choices given in brackets —

When a metallic oxide is dissolved in water, the solution formed has a high concentration of …………… ions. [H⁺, H₃O⁺, OH^-]

Choose the correct answer from the options —

(i) To increase the pH value of a neutral solution, we should add :

1. An acid
2. An acid salt
3. An alkali
4. A salt

(ii) Anhydrous iron [III] chloride is prepared by:

1. Direct combination
2. Simple displacement
3. Decomposition
4. Neutralization

Give one word or a phrase for the statement :
The property by which certain hydrated salts, when left exposed to the atmosphere, lose their water of crystallization and crumble into powder.

State one relevant observation for the following :
Anhydrous calcium chloride is exposed to air for some time.