A photocell is illuminated by a small bright source placed 1 m away. When the same source of light is placed 1 /2 m away, the number of electrons emitted by photocathode would

• decrease by a factor of 4

• increase by a factor of 4

• decrease by a factor of 2

• increase by a factor of 2

The above is a plot of binding energy per nucleon Eb, against the nuclear mass M; A, B, C, D, E, F correspond to different nuclei. Consider four reactions:

(i) A + B → C + ε  (ii) C → A + B + ε
(iii) D + E → F + ε and (iv) F → D + E +ε

where ε is the energy released? In which reaction is ε positive?

This question contains Statement -1 and Statement-2. Of the four choices given after the statements,
Choose the one that best describes the two statements.
Statement – I: Energy is released when heavy nuclei undergo fission or light nuclei undergo fusion.
and
Statement – II: For heavy nuclei, binding energy per nucleon increases with increasing Z while for light nuclei it decreases with increasing Z.

If M₀ is the mass of an oxygen isotope ₈O¹⁷ , Mp and M_N are the masses of a proton and a neutron respectively, the nuclear binding energy of the isotope is

In gamma-ray emission from a nucleus

When ₃Li⁷ nuclei are bombarded by protons, and the resultant nuclei are ₄Be⁸ , the emitted particles will be

The ‘rad’ is the correct unit used to report the measurement of