Question

Identify correct statements from the following:
i. Beryllium oxide is an amphoteric oxide.
ii. Group II elements dissolve in liquid ammonia to form deep blue-black solutions.
iii. The hydration enthalpy of group II ions decreases from $Be ^{2+}$ to $Ba ^{2+}$

• A. i, ii only
• B. ii, iii only
• C. i, iii only
• D. i, ii, iii

Answer 1

Answer: (D)

All the given statements are correct and their explanations are as follows:

(i) Berylium oxide is an amphoteric oxide, i.e. it can react with both acids and bases.

(ii) Group II elements dissolve in liquid ammonia to form deep blue solutions. This blue colour of the solution is due to the ammoniated electron which absorbs energy in the visible region of light and thus impart blue colour to solution.
$M+(x+y) NH _{3} \longrightarrow \left[M\left( NH _{3}\right)_{x}\right]^{2+}+2\left[e\left( NH _{3}\right)_{y}\right]^{-}$

(iii) The hydration enthalpy of group II ions decreases from $Be ^{2+}$ to $Ba ^{2+}$, as the size of cation increases down the group.