Which of the following statements are correct ?
(i) In Sandmeyer reaction nucleophiles like ${\mathrm{Cl}}^{-},{\mathrm{Br}}^{-}$ and ${\mathrm{CN}}^{-}$are indroduced in benzene ring in the presence of ${\mathrm{Cu}}^{+}$ion 
(ii) In Gattermann reaction nucleophiles are introduced in benzene ring in the presence of copper powder and HCI 
(III) The yield in Gattermann reaction is found to be better than Sandmayer reaction.