Assertion (A): Each $s{p}^2$ hybrid orbital has 33.33% s character                                          

Reason (R): Each  $s{p}^3$ hybrid orbital has 25% s character and 75% p character.

The intermixing of one s-orbital and two p-orbitals of an atom to produce three new $s{p}^2$  hybridized orbitals of equivalent energy is called  $s{p}^2$ hybridization.  Hence each $s{p}^2$  hybrid orbitals has 33.33% of s-character and 66.66% of p-character.

The intermixing of one s-orbital and three p-orbitals of an atom to produce four new $s{p}^3$  hybridized orbitals of equivalent energy is called   $s{p}^3$ hybridization.

Hence each $s{p}^3$ hybridized orbital has 25% s-character and 75% p-character.