Dilute hydrochloric acid cannot be concentrated beyond which of the following concentrations by boiling (in $\%$)?

Absolute alcohol cannot be prepared by fractional distillation of rectified spirit since:

Components of a binary mixture of two liquids $A$ and $B$ were being separated by distillation. After some time,the separation of components stopped and the composition of the vapour phase became the same as that of the liquid phase. Both the components started coming in the distillate. Explain why this happened.

Which one of the following mixtures can be separated into pure components by fractional distillation?

An azeotropic solution boils at a temperature lower than the boiling point of any of its components. This solution shows:

Rectified spirit obtained by fermentation contains $4.5 \%$ of water. To remove this water,rectified spirit is mixed with a suitable quantity of benzene and heated. Benzene helps because: