Question

The reaction of lithium with water is less vigorous than that of sodium. It is due to \[ \begin{aligned} \text{I. }& \text{Most negative }E^\circ\text{ value of }\mathrm{Li^+/Li}\\ \text{II. }& \text{Small size of Li}\\ \text{III. }& \text{Very high hydration energy of }\mathrm{Li^+} \end{aligned} \] The correct answer is

• A. I, III only
• B. II, III only
• C. I, II only
• D. I, II, III

Hint:

Lithium behaves anomalously because of \[ \boxed{ \text{small size and high hydration energy of }\mathrm{Li^+}. } \] Hence, lithium reacts less vigorously with water than sodium.

Answer 1

The Correct Option is B

Step 1: Examine Statement I. Although lithium has the most negative standard reduction potential, \[ E^\circ(\mathrm{Li^+/Li})=-3.04\,\text{V}, \] this does not make its reaction with water more vigorous. Hence, Statement I is not the reason.

Step 2: Examine Statements II and III. Lithium has \[ \boxed{\text{very small atomic size}} \] and \[ \boxed{\text{very high hydration energy of }\mathrm{Li^+}.} \] These factors make lithium less reactive towards water than sodium. Thus, Statements II and III are correct.

Step 3: Choose the correct option. Hence, \[ \boxed{\text{Statements II and III only are correct}.} \] Therefore, the correct option is \(\boxed{(B)}\).