Chapter 1 - Introduction and Review - Study Problems - Page 38: 1-38 a

$C_{5}$$H_{5}$$N$

Pyridine consists of a 6 membered ring, containing 5 Carbons and 1 Nitrogen. The Nitrogen has a lone pair (not shown in the given structure) so it has a full octet. Each carbon in the ring has three bonds and no lone pairs, therefore requires one more bond, so each carbon is also bonded to a hydrogen atom, totaling 5 hydrogens.