Which of the following statements is true for all the alkali metals ?

Options

A. Their nitrates decompose on heating to give the corresponding nitridtes and oxygen
B. Their chlorides are deliquescent and crystallise as hydrates
C. They react with water to form hydroxide and hydrogen
D. They readily react with halogens to form ionic halides , `M^(+)X^-`.

Answer

C

Explanation

(A)`4 LiNO_3 to 2Li_2O+4NO_2+O_2`
`2NaNO_3 to 2NaNO_2 + O_2`(similar decomposition with the nitrates of K,Rb and Cs)
(B)Only LiCl is deliquescent and crystallises as a hydrate `LiCl. 2 H_2O`
(C )`2M+2H_2Oto2M^(+)+2OH^(-)+H_2` (M= an alkali metal)
(D) Halides of Li are covalent in nature.