(a) Why photoelectric effect can not be explained on the basis of wave nature of light ? Give reasons.
(b) Write the basic features of photon picture of electromagnetic radiation on which Einstein's photoelectric equation is based.

Write Einstein's photoelectric equation. State clearly how this equation is obtained using the photon picture of electromagnetic radiation. Write the three salient features observed in photoelectric effect which can be explained using this equation.

Write Einsten.s photoelectric equation and point out any two characteristic properties of photons on which this equation is based.

Write Einsteins's equation of photoelectric effect. Give Einstens explanation of photoelectric effect.

(a) When monochromatic light is incident on a surface separating two media, the reflected and refracted light both have the same frequency as the incident frequency. Explain why? (b) When light travels from a rarer to a denser medium, the speed decreases. Does the reduction in speed imply a reduction in the energy carried by the light wave? (c) In the wave picture of light, intensity of light is determined by the square of the amplitude of the wave. What determines the intensity of light in the photon picture of light

Two monochromatic radiations of frequencies v_(1) and v_(2) ( v_(1) gt v_(2) ) and having the same intensity are, in turn, incident on a photosensitive surface to cause photoelectric emission. Explain, giving reason, in which case (i) more number of electrons will be emitted and (ii) the maximum kinetic energy of the emitted photoelectrons will be more.

(i) Write balanced chemical equations only for the following chemical properties of acids: (a) When an acid reacts with a metal. (b) When an acid reacts with a metal bicarbonate. (c ) When an acids reacts with a base. (ii) Three solutions A, B and C has pH values 5,8 and 10 respectively. Amongst the three which solution as maximum hydrogen ion concentration? Classify the nature of the three solutions as acidic or basic?

(a) Cite the evidence on the basis of which it is concluded that birds have evolved from reptiles. (b) Insects, Octopus, Planaria and Vertebrates also possess eyes. Can these animals be grouped together on the basis of the eyes they possess. Why or why not? Give reason to justify your answer.