Since D of D2O gets attached to the carbon atom to which MgBr is attached, C is isopropylmagnesium bromide
Therefore, the compound R-Br is 2- bromopropane
When an alkyl halide is trated with Na in the presence of ether, a hydrocarbon containing double bond the number of carbon atom as present in the original halide is obtained as product. This is known as Wurtz raction.