`R -Mg-Br(A)` on reaction with `H_(2)O` forms a gas `(B)`, which occupied `1.4 L//g` at `NTP`. What is product when `R-Br` reacts with benzene in presence of `AICI_(3)`?

Explanation

`underset([A])(R-Mg-Br)+H_(2)Otounderset("Alkane (gas)")(R-H)+Mg(OH)Br`
`1*4L` of gas are evolved at N.T.P. from alkane `=1g`
`22*4`L of gas are evolved at N.T.P. from alkane `=((1g))/((1*4L))xx(22*4L)=16g`
`therefore` The alkane is `CH_(4)` and alkyl group (R) is methyl `(CH_(3))` group. the reaction taking place are
`underset([A])(CH_(3)-Mg-Br)+H_(2)OtoCH_(4)+Mg(OH)Br`