# Hydrazinium ion is

$(a)\;N_2H_3^-\qquad(b)\;N_2H_3^+\qquad(c)\;H_5 N_2^+\qquad(d)\;N_2H_5^-$

Hydrazinium ion is $N_2H_5^+$
Hydrazinium is the cation with the formula $N_2H_5^{+}$
Hydrazinium is derived from hydrazine by protonation Salts of hydrazinium are common reagents in chemistry and are often used in certain industrial processes.
Hence (c) is the correct answer.
edited Feb 26