Which of the following is a low-boiling azeotropic mixture?

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

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:

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 is the correct statement? If an azeotropic solution of two liquids has a boiling point higher than both of them,then it:

$A$ dilute solution of $HCl$ cannot be concentrated beyond ...... $\%$ by boiling.