A solution of alcohol in water has been prepared by mixing 150 ml of alcohol with 600 ml of water. Calculate the volume percentage of the solution.

A compound 'P' forms the enamel of teeth. It is the hardest substance of the body. It doesn't dissolve in water but gets corroded when the pH is lowered below 5.5. (a) Identify the compound 'P.' (b) How does it undergo damage due to the eating of chocolate and sweets? What should we do to prevent tooth decay?

A dry pellet of a common base 'B', when kept in open, absorbs moisture and turns sticky. The compound is also formed by chloralkali process. Identify B. What type of reaction occurs when B is treated with dilute hydrochloric acid. Write the chemical equation.

Why is plaster of Paris written as CaSO₄ . 1/2 H₂O? How is it possible to have half a water molecule attached to CuSO₄?

Why alkalis like sodium hydroxide and potassium hydroxide should not be left exposed to air?