The reaction of an alkyl halide with $Mg$ in dry ether produces ..... as the product.

Which sequence of reagents is useful for the conversion of $C_6H_5CH_2CH_3$ to $C_6H_5CH=CH_2$?

The chlorine atom of the following compound that reacts most readily with $AgNO_3$ to give a precipitate is

$2CHCl_3 + O_2 \xrightarrow{X} 2COCl_2 + 2HCl$. In the above reaction,$X$ stands for:

The order of reactivity of the following halides towards $S_{N}1$ reaction is:
$(1) \ (CH_3)_3CBr$
$(2) \ (C_6H_5)_2CHBr$
$(3) \ (C_6H_5)_2C(CH_3)Br$
$(4) \ (CH_3)_2CHBr$
$(5) \ C_2H_5Br$

The major product obtained from the reaction of $2$-bromopentane with potassium ethoxide in ethanol is ....................