Explain why phenol with bromine water forms $2,4,6$-Tribromophenol while on reaction with bromine in ${\mathrm{CS}}_2$ at low temperatures forms para-bromophenol as the major product.

Write the structure of the following compound:

$\alpha$-Methoxypropionaldehyde

Write the structure of the following compound:

$3$-Hydroxybutanal

Write the structure of the following compound:

$2$-Hydroxycyclopentanecarbaldehyde

Write the structure of the following compound:

$4$-Oxopentanal

Write the structure of the following compound.

Di-sec. butyl ketone 

Write the structure of the following compound.

$4$-Fluoroacetophenone

Write the structures of products of the following reaction:

Write the structures of products of the following reaction:

${\mathrm{H}}_3\mathrm{C}-\mathrm{C}\equiv \mathrm{C}-\mathrm{H}\stackrel{\mathrm{H}{\mathrm{g}}^{2+}, {\mathrm{H}}_2\mathrm{S}{\mathrm{O}}_4}{\to }$