A leaf which contains only green pigments, is illuminated by a laser light of wavelength $0.6328 \mu \mathrm{m}$. It would appear to be

If an object reflects the colour of light incident on it, it will appear with that colour but if object absorbs the colour of light, it will appear to be black. Since the given wavelength does not belong to green, so it will be absorbed by the leaf and hence, it will appear to be black.