Silver Bromide on exposure to sunlight turns grey due to:

Four students were asked to study the reaction between aqueous solutions of barium chloride and sodium sulphate. On mixing the solutions of the two salts in a test tube, they reported their experiment as follows:
$\left(\mathrm{i}\right)$ the colour of the mixture becomes brown
$\left(\mathrm{ii}\right)$ the solutions form separate layer
$\left(\mathrm{iii}\right)$ a colourless mixture is obtained
$\left(\mathrm{iv}\right)$ a white substance settles at the bottom

The correct report is