One mole of $N_2H_4$ loses 10 mole electrons to form a new compound Y. Assuming that all the $N_2$ appears in new compound, what is the oxidation state of Nitrogen in Y? (There is no change in the oxidation state of H)

Question

$\begin{array}{1 1} (a)\;+2 \\(b)\;+3 \\ (c)\;-4 \\ (d)\;+5 \end{array} $