Which of the following is an alkali metal?

Which one of the following reacts with concentrated sulphuric acid?

Which of the following statements are correct for alkali metal compounds?
$(i)$ Superoxides are paramagnetic in nature.
(ii) The basic strengths of hydroxides increase down the group.
(iii) The conductivity of chlorides in their aqueous solutions decreases down the group.
(iv) The basic nature of carbonates in aqueous solutions is due to cationic hydrolysis.

Sodium hydroxide is produced on a large scale:

Which one of the following elements reduces $NaOH$ to $Na$?

The blue colour of the solution (metal dissolved in liquid ammonia) is due to