Heating methyl chloride with zinc in a closed tube produces...............

What is the correct order of reactivity of alkyl halides towards dehydrohalogenation?

Alkyl halides react with $Mg$ in dry ether to form

The decreasing order of reactivity towards dehydrohalogenation $(E_1)$ reaction of the following compounds is:
$(A)$ $CH_3CH_2CH_2CH_2Cl$
$(B)$ $CH_2=CHCH_2CH_2Cl$
$(C)$ $CH_3CH_2CHClCH_3$
$(D)$ $CH_2=CHCHClCH_3$

Identify the product $A$ in the following reaction: $C_2H_5Br + \text{aq. } KOH \rightarrow A + KBr$

The major product obtained from $E_{2}$-elimination of $3$-bromo-$2$-fluoropentane is