Choose the correct statements from the following.

Options

A. Beryllium is not readily attacked by acids because of the presence of an oxide film on the surface of the metal
B. Beryllium sulphate is readily soluble in water as the greater hydration enthalpy of `Be^(2+)` overcomes the lattice ethalpy factor
C. Beryllium exhibits coordination number more than four
D. Beryllium oxide is purely acidic in nature

Answer

A, B

Explanation

Due to diagonal relationship, beryllium is similar to aluminium. It also forms an oxide film which is very stable on the surface of the metal. Beryllium sulphate is soluble in water due to high hydration energy. Beryllium does not exhibit coordination number more than four. Like `AI_(2)O_(3),BeO` is amphoteric in nature.
Note The anomalous behaviour of Be is mainly due to its very small size and partly due to its high electronegativity. These two factors increase the polarising power of `Be^(2+)` ions of such extent that it becomes significantly equal to the polarising power of `AI^(3+)` ions. Therefore, these two elements, Be and AI resemble (diagonal relationship) very much.
Polarising power `= ("Ionic chgarge")/(("Ionic radii")^(2))`