When $1$-bromo-$2$-butene is treated with magnesium metal in dry ether, a Grignard reagent is formed. Addition of water to Grignard reagent gives a mixture of $1$-butene and $2$-butene. Further, $3$-bromo-$1$-butene under similar treatment gives the same products. Explain.

Give steps involved in the following transformation using Grignard synthesis.

Give the products for the viable reactions.

 Give products for the viable reactions.

 $n-{\mathrm{C}}_4{\mathrm{H}}_9\mathrm{I}+\mathrm{Zn}⟶$

Give the products for the viable reactions.

 $\mathrm{n}-{\mathrm{C}}_4{\mathrm{H}}_9\mathrm{Cl}+\mathrm{Zn}⟶$

Explain the following.

 ${\mathrm{BrCH}}_2\mathrm{C}\equiv \mathrm{CH}$ cannot be converted into corresponding Grignard or organolithium reagent.