Question

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

• A. Their nitrates decomposes on heating to give the corresponding nitrites and oxygen
• B. Their chlorides are deliquescent and crystallize as hydrates.
• C. They react with water to form hydroxide and hydrogen.
• D. They react with halogens to form only ionic halides $M^{+}X^{-}$ .

Answer 1

Answer: (C)

$\left(\text{A}\right) \, 4 \, \left(\text{LiNO}\right)_{\text{3}} \rightarrow 2 \, \left(\text{Li}\right)_{\text{2}} \text{O} \, + \, 4 \, \left(\text{NO}\right)_{\text{2}} \, + \, \left(\text{O}\right)_{\text{2}}$

$2 \, \text{NaNO}_{\text{3}} \rightarrow 2 \, \text{NaNO}_{\text{2}} + \text{O}_{\text{2}}$ similar decomposition with the nitrates of $\text{K,} \, \text{Pb}$ and $\text{Cs}$ )

$\left(B\right)$ Only $\text{LiCl}$ is deliquescent and crystallises as a hydrate $\text{LiCl}$ . $2H_{2}O$

$\left(\text{C}\right) \, 2 \, \text{M} + 2 \, \left(\text{H}\right)_{\text{2}} \text{O} \rightarrow 2 \, \left(\text{M}\right)^{\text{+}} + 2 \, \left(\text{OH}\right)^{-} + \left(\text{H}\right)_{\text{2}}$ (M is an alkali metal)

$\left(D\right)$ Halides of $\text{Li}$ are covalent in nature.