Copper sulphate solution is electrolysed with platinum electrodes. Which of the following changes does not occur in the process?

(1) The blue colour of the solution gradually fades 
(2) O₂(g) is liberated at anode 
(3) pH of the solution decreases 
(4) H⁺ concentration decreases

The compound containing both covalent and ionic bond is

(1) MgCl₂
(2) NH₄Cl
(3) CaO
(4) AlBr₃

Which of the following salt does not contain the water of crystallization ?

(1) blue vitriol
(2) baking soda
(3) washing soda
(4) gypsum

The concentration of hydroxide ion in a solution is 1 × 10^–10 mole per litre. Its pH value will be:

(1) 4
(2) 8
(3) 10
(4) –10

Which of the following does not form salt with alkali but forms with acid?

(1) BeO
(2) ZnO
(3) CaO
(4) SnO