sblock Elements 2 Question 5
5. The structures of beryllium chloride in the solid state and vapour phase, respectively are
(2019 Main, 9 April II)
(a) dimeric and dimeric
(b) chain and chain
(c) dimeric and chain
(d) chain and dimeric
Show Answer
Answer:
Correct Answer: 5. (c)
Solution: The structures of beryllium chloride in the solid state and vapour phase, respectively are dimeric and chain. In vapour phase at above $900^{\circ} \mathrm{C}, \mathrm{BeCl}_2$ is monomeric having a linear structure Cl $-\mathrm{Be}-\mathrm{Cl}$. The bonding in $\mathrm{BeCl}_2$ is covalent and Be atom accommodates $2+2=4$ electrons in the two $s p$-hybrid orbitals. Below $900^{\circ} \mathrm{C}$, beryllium chloride in vapour phase exists as a mixture of monomer $\mathrm{BeCl}_2$ and dimer $\mathrm{Be}_2 \mathrm{Cl}_4$.
BETA
