Which of the following statements about beryllium compounds are correct?

AAnhydrous beryllium chloride dissolves in diethyl ether
BBeryllium chloride has a higher melting point than magnesium chloride because Be2+ is smaller
CBe(II) in water exists as $[Be (H X_{2} O) X_{6}] X^{2 +}$
DAqueous solutions of beryllium salts are acidic because of hydrolysis of $[Be (H X_{2} O) X_{4}] X^{2 +}$

Answer: A, D

The tiny Be2+ polarises coordinated water so

[Be (H X_{2} O) X_{4}] X^{2 +}

is acidic, and covalent BeCl2 dissolves in ether. Be has a maximum coordination number of 4 (no

[Be (H X_{2} O) X_{6}] X^{2 +}

), and covalent BeCl2 (about 688 K) melts lower than ionic MgCl2 (about 987 K).