Question

How many of the following are planar?
$C(CN{)}_3^{–},\stackrel{\bullet }{\text{C}}{\text{H}}_3,\stackrel{(+)}{\text{C}}{\text{H}}_3,H_{2}O$, Polymeric $Be{H}_2$, Polymeric $BeC{l}_2,B_2{H}_6,C_2{H}_2,N{O}_2^{+},N{O}_2,N{O}_2^{–},Ni(CO{)}_4,[Zn(OH{)}_4{]}^{2–}$

Answer 1

$C(CN{)}_3^{–}$ is planar because there is bonding between $C\left(2p\right)CN–\left({\pi }^{\ast }\right)$ so this is planar
$\stackrel{\bullet }{\text{C}}{\text{H}}_3\to s{p}^2$
$\stackrel{(+)}{\text{C}}{\text{H}}_3\to s{p}^2$
$N{O}_2^{+},N{O}_2^{–},\stackrel{\bullet }{\text{N}}{\text{O}}_2\to$ planar,
$H_{2}O\to$ planar