Question

Which one of the following molecules/ions does not exist?

• A. $L{i}_2$
• B. $B{e}_2$
• C. $B_2$
• D. $B{e}_2^{+}$

Answer 1

Answer: (B)

$B{e}_2$ does not exist.
$B{e}_2$ has an electronic configuration of :
$\sigma 1s^2{\sigma }^{\ast }1s^2\sigma 2s^2{\sigma }^{\ast }2s^2$
$\therefore$ Bond order $=\frac{4-4}{3}=0$
Thus, $B{e}_2$ does not exist.