Which of the following is not an element?

Which of the following substances consists of only one element?

In the fractional distillation of crude petroleum,which of the following statements is correct?

$A$ mixture of camphor and benzoic acid can be separated by:

The separation of two coloured substances was done by paper chromatography. The distances travelled by solvent front,substance $A$ and substance $B$ from the base line are $3.25 \ cm$,$2.08 \ cm$ and $1.05 \ cm$ respectively. The ratio of $R_{f}$ values of $A$ to $B$ is $.........$

How will you separate a miscible solution of benzene and $CHCl_3$?