Choose the correct statement(s):
A. Beryllium oxide is purely acidic in nature.
B. Beryllium carbonate is kept in the atmosphere of CO$$_2$$.
C. Beryllium sulphate is readily soluble in water.
D. Beryllium shows anomalous behavior.

We need to identify the correct statements about Beryllium.

Statement A says Beryllium oxide is purely acidic in nature. This is false — Beryllium oxide (BeO) is actually amphoteric. It reacts with both acids and bases:

$$BeO + 2HCl \rightarrow BeCl_2 + H_2O$$

$$BeO + 2NaOH \rightarrow Na_2BeO_2 + H_2O$$

Statement B says Beryllium carbonate is kept in the atmosphere of CO$$_2$$. This is true — BeCO$$_3$$ is unstable and decomposes readily, so it is kept in an atmosphere of CO$$_2$$ to prevent decomposition.

Statement C says Beryllium sulphate is readily soluble in water. This is true — unlike other alkaline earth metal sulphates (like BaSO$$_4$$), BeSO$$_4$$ is readily soluble in water due to the high hydration energy of the small Be$$^{2+}$$ ion.

Statement D says Beryllium shows anomalous behavior. This is true — Beryllium shows anomalous behavior compared to other members of Group 2 due to its very small size, high ionization energy, and high electronegativity, and it shows a diagonal relationship with aluminium.

So, the correct statements are B, C, and D only.