Which of the following statement(s) is (are) correct? (i) $\mathrm{LiF}$ is less soluble in water (ii)…
Which of the following statement(s) is (are) correct?
(i) $\mathrm{LiF}$ is less soluble in water
(ii) $\mathrm{NaCl}$ is less ionic than $\mathrm{CsCl}$
(iii) Formation of alkali metal halide is an endothermic reaction
i \& ii only
i, ii \& iii
ii \& iii only
i only
Solution
LiF being predominantly covalent, has a high lattice enthalpy due to which it is less soluble in water. Thus, (i) is correct.
$\mathrm{Na}^{+} < \mathrm{Cs}^{+}$so the polarizing power of $\mathrm{Na}^{+}$is higher than that of $\mathrm{Cs}^{+}$which results in $\mathrm{NaCl}$ being more covalent or less ionic than $\mathrm{CsCl}$.
Thus, (ii) is also correct.
Formation of alkali metal halides like $\mathrm{NaCl}, \mathrm{CsCl}, \mathrm{KF}$, etc. is an exothermic reaction which gives rise to a stable crystal lattice.
Thus, (iii) is incorrect.