Choose the correct statement(s) :
A. Beryllium oxide is purely acidic in nature.
B. Beryllium carbonate is kept in the atmosphere of CO₂.
C. Beryllium sulphate is readily soluble in water.
D. Beryllium shows anomalous behaviour.
Choose the correct answer from the options given below :

Solution

Chemistry ma’am · 3 steps

Beryllium oxide is amphoteric, not purely acidic. Strike out A and the other three stand.

1. Why Be is different. The Be²⁺ ion is tiny and highly charged, so it polarises its neighbours strongly and its compounds are largely covalent. That is the root of beryllium's anomalous behaviour, so D is correct.

   Statement	True or false	Reason
   A: BeO is purely acidic	False	BeO is amphoteric. It dissolves in acids and in alkalis.
   B: BeCO₃ kept under CO₂	True	BeCO₃ readily loses CO₂ (BeCO₃ ⇌ BeO + CO₂). Excess CO₂ pushes this equilibrium back to the left.
   C: BeSO₄ readily soluble	True	The small Be²⁺ ion has a very high hydration enthalpy. This outweighs the lattice enthalpy.
   D: Be is anomalous	True	Small size, high charge density and no d orbitals make it unlike the rest of group 2.

2. Amphoteric oxide. BeO + 2HCl → BeCl₂ + H₂O and BeO + 2NaOH → Na₂BeO₂ + H₂O. An oxide that reacts with both acids and bases cannot be called purely acidic.
3. So. B, C and D are correct and A is wrong, which is option (b).

The idea to keep. For Be, think small ion, high charge density. That one idea explains its amphoteric oxide, unstable carbonate, soluble sulphate and its overall anomalous behaviour.

Answer from the NTA final answer key. Solution by PrepWiser.