Solution

$$a)Monovalent \ material$$
$$1$$ eq. mass of the substance requires $$96500$$ coulombs
Since the element is monatomic, thus equivalent mass = molecular mass
$$6.023\times 10^{23}$$ atoms require $$96500C$$
$$1$$ atoms require $$=\dfrac { 96500 }{ 6.023\times 10^{23} } C=1.6\times 10^{-19}C$$

$$(b)Divalent \ material$$
Since the element is diatomic, thus equivalent mass $$=\dfrac{molecular \ mass}{2}$$
$$=\dfrac{1\times 6.023\times 10^{23}}{2}$$ atoms require $$96500C$$
$$1$$ atoms require $$=\dfrac { 96500\times 2 }{ 6.023\times 10^{23} } C=3.2\times 10^{-19}C$$