Which statement is not correct

Pure Alkyl Bromides are colourless 

Alkyl Bromides and iodides develop color when exposed to light

$\mathrm{R}-{\mathrm{NO}}_2$ is obtained  as a major product on reaction between  $\mathrm{R}-\mathrm{X}$ and  ${\mathrm{AgNO}}_2$

$\mathrm{R}-\mathrm{CN}$ is obtained as a major product on reaction between $\mathrm{R}-\mathrm{X}$ and  $\mathrm{AgCN}$