Which type of overlapping results in the formation of a $\pi$ bond?

Which type of bond is formed by the linear overlap of two hybrid orbitals,each containing one electron,associated with two different atoms?

Which of the following statements is $NOT$ true regarding the sigma and pi bonds formed between two carbon atoms?

If the internuclear axis of a diatomic molecule is $z$,then the overlap of $p_x$ and $p_y$ orbitals results in the formation of ........

Match the orbital overlap figures shown in List-$I$ with the description given in List-$II$ and select the correct answer using the code given below the lists.
List-$I$:
$P$. Two $d$-orbitals overlapping axially with same phase.
$Q$. $A$ $p$-orbital and a $d$-orbital overlapping laterally with same phase.
$R$. $A$ $p$-orbital and a $d$-orbital overlapping laterally with opposite phase.
$S$. Two $d$-orbitals overlapping axially with opposite phase.
List-$II$:
$1$. $p-d$ $\pi$ antibonding
$2$. $d-d$ $\sigma$ bonding
$3$. $p-d$ $\pi$ bonding
$4$. $d-d$ $\sigma$ antibonding
Codes: $P \quad Q \quad R \quad S$

Explain $\sigma$ bond formed by $s-s$,$s-p$ and $p-p$ overlapping.