Which of the following statements about alkali metals are correct?

ASodium burns in excess dry oxygen to give mainly the normal oxide $Na X_{2} O$ .
BLithium is the strongest reducing agent among the alkali metals in aqueous solution.
CCaesium has the lowest first ionisation enthalpy among the stable alkali metals.
DLithium is the only alkali metal that combines directly with nitrogen to form $Li X_{3} N$ .

Answer: B, C, D

Li has the most negative

E^{\circ}

(about

- 3.04 V

) because of its large hydration enthalpy, Cs has the lowest ionisation enthalpy, and Li is the only alkali metal that combines directly with

N X_{2}

to give

Li X_{3} N

. Sodium burns in excess oxygen to give mainly the peroxide

Na X_{2} O X_{2}

, so the fourth statement is wrong.