Question: How many hydrogens are present around each carbon atom in the following molecules?

a.

b.

Every junction and terminal position of the skeletal structure represents a carbon atom. Assign the carbon atom at every junction and terminal position.

As per the tetravalency of carbon, assign hydrogen atoms to all the carbon atoms.

Note: Do not assign hydrogen atoms to any heteroatom.

Count the number of electrons around each carbon atom and check the octet.

Assign lone pair of electrons on all heteroatoms to complete their octet.

The carbon atoms are placed at all the junctions and terminal positions. All these carbon atoms are assigned hydrogen atoms to complete their octet.

a. The carbon atoms with already complete octet are not assigned any hydrogen atom. Such carbon atoms are marked with a $\left(*\right)$. The heteroatoms are not assigned with any hydrogen atoms.

Structure of a

b. The carbon atoms with already complete octet are marked with a $\left(*\right)$. The heteroatoms are not assigned with any hydrogen atoms.

Structure of b