Bromoethane reacts with $\mathrm{AgNO}{}_2$ to give mainly

$\mathrm{NO}{}_2{}^{-}$ is ambident. The covalent $\mathrm{AgNO}{}_2$ makes the lone pair on nitrogen available, so bonding is through N and $\mathrm{CH}{}_3\mathrm{CH}{}_2\mathrm{NO}{}_2$ (nitroethane) is the main product. Ionic $\mathrm{KNO}{}_2$ gives mostly the alkyl nitrite.