What is collected in the flask at the end in steam distillation?

Give a brief description of the principles of the following techniques taking an example in each case. $(a)$ Crystallisation $(b)$ Distillation $(c)$ Chromatography

Suggest a method for the purification of camphor contaminated with salt.

Which one of the following techniques is not used to spot components of a mixture separated on a thin layer chromatographic plate?

Fill in the blanks:
$1$. In formulas and reactions,the electron pair displacement is indicated by a curved arrow,and the single electron displacement is indicated by a ..........
$2$. There are more than .......... plates in the columns of fractional distillation.
$3$. Fractional distillation is used for the separation of liquids with a .......... difference in boiling points,and simple distillation is used for the separation of liquids with a .......... difference in boiling points.
$4$. The .......... technique is applied to separate different fractions of crude oil in petroleum.

The most suitable method of separation of a $1:1$ mixture of $ortho$- and $para$-nitrophenols is: