The halide shown is converted to its Grignard reagent with magnesium in dry ether, and the resulting solution is then treated with water. Which structure is the main organic product?

A Grignard reagent behaves as a carbanion and is a strong base; water protonates it to the alkane. Isopropylmagnesium bromide gives propane and $\mathrm{Mg}(\mathrm{OH})\mathrm{Br}$. Propan-2-ol would need oxygen insertion, and the coupled hydrocarbon is only a minor Wurtz-type by-product.