What happens when white light is incident on a white object?

When white light is incident on a blue pigment,which colors of light are reflected?

Sushil went to an eye specialist for a check-up. The doctor prescribed him to use spectacle lenses of $+0.5 \text{ D}$ power.
$(a)$ Name the defect of vision he is suffering from.
$(b)$ Find the focal length of the spectacle lens.

$A$ prism $ABC$ (with $BC$ as base) is placed in different orientations. $A$ narrow beam of white light is incident on the prism as shown in the figure. In which of the following cases,after dispersion,the third colour from the top corresponds to the colour of the sky?

How is long-sightedness corrected?

What is the phenomenon of splitting of white light into its seven constituent colors called?