Polysubstitution is a major drawback in:

If p is the momentum of the fastest electron ejected from a metal surface after the irradiation of light having wavelength $$\lambda $$, then for 1.5 p momentum of the photoelectron, the wavelength of the light should be: (Assume kinetic energy of ejected photoelectron to be very high in comparison to work function)

Fructose and glucose can be distinguished by :

The major product obtained in the following reaction is