Ethylene glycol,on oxidation with periodic acid $(HIO_4)$,gives:

What is obtained by the reaction of primary and secondary alcohols with red-hot copper?

Which of the following has the highest boiling point?

In the following reaction sequence,$CH_3CH_2OH$ $\xrightarrow{P + I_2} A$ $\xrightarrow[\text{dry ether}]{Mg} B$ $\xrightarrow{HCHO} C$ $\xrightarrow{H_2O} D$,the compound $D$ is:

$CH \equiv CH$ $\xrightarrow{Hg^{2+}/H_2SO_4} B$ $\xrightarrow{CH_3MgX/H_2O} C$ $\xrightarrow{[O]} D$. What is the final product $D$?

Which is the best method to prepare cycloalkene from cyclohexanol?