Classical mechanics does not provide satustactory explanation tor the tollowing: (a) Black-body radiation (b) Photoelectric effect (c) Heat capacities of solids (d) All the above

The first step is to understand each of the listed concepts and their explanation or lack thereof in classical mechanics. Black-body radiation refers to the radiation emitted by an idealized physical body called a black body. The Photoelectric effect is the emission of electrons when light hits a material. Heat capacity of solids refers to the amount of heat that must be added to a solid to raise its temperature.

Black-body radiation cannot be explained by classical mechanics as the theory predicted unlimited energy which deviates from experimental evidence, leading to what is known as the ‘ultraviolet catastrophe’. In the case of the photoelectric effect, classical wave theory of light predicts that the energy of electrons emitted in the photoelectric effect would depend on the intensity of incident light, but experiments showed that they depend on the frequency of incident light. This cannot be explained by classical mechanics. The heat capacities of solids observed experimentally, at low temperatures, deviate significantly from Dulong-Petit law, which is predicted by classical mechanics. Therefore, classical mechanics is insufficient to explain these observations.

Since classical mechanics does not provide satisfactory explanation for all the listed phenomena, the answer to the question is (d) All of the above.