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 Multiple Choice QuestionsMultiple Choice Questions

11.

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 biological effect of radiation


D.

the biological effect of radiation

199 Views

12.

If the binding energy per nucleon in Li presubscript 3 presuperscript 7and He presubscript 4 presuperscript 2 nuclei are 5.60 MeV and 7.06 MeV respectively, then in the reaction

straight p space plus space Li presubscript 3 presuperscript 7 space rightwards arrow with space on top space 2 space He presubscript 2 presuperscript 4
energy of proton must be

  • 39.2 MeV

  • 28.24 MeV

  • 17.28 MeV

  • 1.46 MeV


C.

17.28 MeV

EP = (8 × 7.06 – 7 × 5.60) MeV
= 17.28 MeV

138 Views

13.

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 proton number changes


B.

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

132 Views

14.

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 – 1 is true, Statement – 2 is False.


D.

Statement – 1 is true, Statement – 2 is False.

184 Views

15.

A nucleus of mass M + Δm is at rest and decays into two daughter nuclei of equal mass M/2 each. Speed of light is c.

The speed of daughter nuclei is

  • fraction numerator increment straight m over denominator straight M plus increment straight m end fraction
  • square root of fraction numerator 2 increment straight m over denominator straight M end fraction end root
  • straight c square root of fraction numerator increment straight m over denominator straight M end fraction end root
  • straight c space square root of fraction numerator increment straight m over denominator straight M space plus space increment straight m end fraction end root

B.

square root of fraction numerator 2 increment straight m over denominator straight M end fraction end root

Conserving the momentum
0 space equals space space straight M over 2 straight V subscript 1 space minus space straight M over 2 space straight V subscript 2 space left parenthesis therefore space initial space Velocity space equals space 0 right parenthesis
rightwards double arrow space straight v subscript 1 space equals space straight v subscript 2 space..... space left parenthesis straight i right parenthesis
Now, from energy conservation and mass -energy equivalence

401 Views

16.

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

  • (M08MP) C2

  • (M08MP9MN) C2

  • M0C2

  • (M017 MN) C2


B.

(M08MP9MN) C2

160 Views

17.

A nucleus of mass M + Δm is at rest and decays into two daughter nuclei of equal mass M/2 each. The speed of light is c.
The binding energy per nucleon for the parent nucleus is E1 and that for the daughter nuclei is E2. Then

  • E1 = 2E2

  • E2 = 2E1

  • E1 > E2

  • E2 > E1


D.

E2 > E1

After decay, the daughter nuclei will be more stable hence, binding energy per nucleon will be more than that of their parent nucleus.

347 Views

18.

The transition from the state n = 4 to n = 3 in a hydrogen-like atom results in ultraviolet radiation. Infrared radiation will be obtained in the transition from

  • 2 → 1

  • 3 → 2

  • 4 → 2

  • 5→ 4


D.

5→ 4

IR corresponds to least value of open parentheses fraction numerator 1 over denominator straight n subscript 1 superscript 2 end fraction minus fraction numerator 1 over denominator straight n subscript 2 superscript 2 end fraction close parentheses i.e. from Paschen, Bracket and Pfund series. Thus the transition corresponds to 5 → 4

139 Views

19.

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 decay at same rate always


B.

Y will decay faster than X

straight t subscript 1 divided by 2 end subscript space equals space fraction numerator In space 2 over denominator straight lambda subscript straight x end fraction
straight tau subscript mean space equals 1 over straight lambda subscript straight y semicolon space dN over dt space equals space minus space λN
fraction numerator In 2 over denominator straight lambda subscript straight x end fraction space equals space 1 over straight lambda subscript straight y space
rightwards double arrow space straight lambda subscript straight x space equals space straight lambda subscript straight y space left parenthesis 0.6932 right parenthesis
rightwards double arrow space straight lambda subscript straight y space greater than space straight lambda subscript straight x
114 Views

20.

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?

  • (i) and (iv)

  • (i) and (iii)

  • (ii) and (iv)

  • (ii) and (iii)


A.

(i) and (iv)

Binding energy per nucleon of each product is less than that of each reactant.

424 Views