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.

• Statement – 1is false, Statement – 2 is true.

• Statement – 1is true, Statement – 2 is true; Statement -2 is correct explanation for Statement-1.

• Statement – 1is true, Statement – 2 is true; Statement -2 is not a correct explanation for Statement-1.

• Statement – 1is true, Statement – 2 is true; Statement -2 is not a correct explanation for Statement-1.

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

• (M₀ – ⁸M_P) C²

• (M₀ – ⁸M_P – ⁹M_N) C²

• M₀C²

• M₀C²

In gamma-ray emission from a nucleus

• both the neutron number and the proton number change

• there is no change in the proton number and the neutron number

• only the neutron number changes

• only the neutron number changes

The half-life period of a radio-active element X is same as the mean life-time of another radio-active element Y. Initially, they have the same number of atoms. Then

• X will decay faster than Y

• Y will decay faster than X

• X and Y have same decay rate initially

• X and Y have same decay rate initially

15.

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

• neutrons

• alpha particles

• beta particles

• beta particles

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

• the rate of decay of radioactive source

• the ability of a beam of gamma ray photons to produce ions in a target

• the energy delivered by radiation to a target.

• the energy delivered by radiation to a target.

If the binding energy per nucleon in and nuclei are 5.60 MeV and 7.06 MeV respectively, then in the reaction


energy of proton must be

• 39.2 MeV

• 28.24 MeV

• 17.28 MeV

• 17.28 MeV

The intensity of gamma radiation from a given source is I. On passing through 36 mm of lead, it is reduced to l/8. The thickness of lead which will reduce the intensity to l/2 will be

• 6 mm

• 9 mm

• 18 mm

• 18 mm

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

• decrease by a factor of 2

Starting with a sample of pure ⁶⁶Cu, 7/8 of it decays into Zn in 15 minutes. The corresponding half-life is

• 10 minutes

• 15 minutes

• 5 minutes

• 5 minutes