The total number of hydrogen atoms in product A and product B is__________.

When bromoethane reacts with $\mathrm{NaOH}$ in the presence of ethyl alcohol gives Ethene. 

Similarly When bromoethane reacts with $\mathrm{NaOH}$ in the aqueous medium gives Ethyl alcohol. This reaction is an example of a nucleophilic substitution reaction.

The reaction is as follows,

Total number of hydrogen atom in $\mathrm{A}$ that is Ethene and $\mathrm{B}$ that is  Ethyl alcohol is $10$