Which one of the following compounds is used as a chemical in certain types of fire extinguishers?

Which of the alkali metals has the lowest melting point?

The chemical formula of feldspar is

$X$ $\xrightarrow{N_2, \Delta} Y$ $\xrightarrow{H_2O} Z$ (colourless gas) $\xrightarrow{CuSO_4} T$ (blue colour)
Then,substances $Y$ and $T$ are

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.

Alkali metals dissolve in liquid ammonia to give a deep blue solution. This blue color is due to which of the following?