The nodal plane in an ethylene $(C_2H_4)$ molecule is:

How and when is a $\pi$-bond formed by the overlapping of orbitals?

$A$ molecule $(X)$ has $(i)$ four sigma bonds formed by the overlap of $sp^2$ and $s$ orbitals,(ii) one sigma bond formed by $sp^2$ and $sp^2$ orbitals,and (iii) one $\pi$ bond formed by $p_z$ and $p_z$ orbitals. Which of the following is $X$?

The $d_{xy}$ orbital can form a $\pi$ bond with another $d_{xy}$ orbital along which axis?

The number of $\sigma$ and $\pi$ bonds in $2-$formylbenzoic acid are respectively

Assertion : Sigma $(\sigma)$ is a strong bond,while pi $(\pi)$ is a weak bond.
Reason : Atoms rotate freely about pi $(\pi)$ bond.