Which of the following molecules possesses a bond formed by $sp^2-sp$ orbital overlap?

What is the total number of sigma $(\sigma)$ and pi $(\pi)$ bonds in the following molecules?
$(a)$ $C_{2}H_{2}$
$(b)$ $C_{2}H_{4}$

Assuming the bond direction is along the $z$-axis,which of the following overlaps of atomic orbitals of two atoms $(A)$ and $(B)$ will result in bonding?
$I$. $s$-orbital of $A$ and $p_x$-orbital of $B$
$II$. $s$-orbital of $A$ and $p_z$-orbital of $B$
$III$. $p_y$-orbital of $A$ and $p_z$-orbital of $B$
$IV$. $s$-orbital of both $(A)$ and $(B)$

Indicate the $\sigma$ and $\pi$ bonds in the following molecules:
$C_{6}H_{6}, C_{6}H_{12}, CH_{2}Cl_{2}, CH_{2}=C=CH_{2}, CH_{3}NO_{2}, HCONHCH_{3}$

Considering the $X$-axis as the internuclear axis,which of the following will not form a sigma $(\sigma)$ bond and why?

In a diatomic molecule,the internuclear axis is $Z$. Which of the following bonds will be formed by the overlap of $P_x$ and $P_y$ orbitals?