Alcohols Phenols And Ethers

2-Methyl propyl bromide reacts with \(\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{O}^{-}\) and gives 'A' whereas on reaction with \(\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{OH}\) it gives 'B'. The mechanism followed in these reactions and the products 'A' and 'B' respectively are :