Assertion:  It is not possible to use  ³⁵Cl  as  the fuel for fusion energy.

Reason: The binding energy of  ³⁵Cl is too small.

• If both assertion and reason are true and reason is the correct explanation of assertion

• If both assertion and reason are true but reason is not the correct explanation of assertion

• If assertion is true but reason is false

• If both assertion and reason are false

Assertion: The number of electrons in a p-type silicon  semiconductor is less than the number of electrons in a pure silicon semiconductor at room temperature.

Reason: It is due to law of mass action.

• If both assertion and reason are true and reason is the correct explanation of assertion

• If both assertion and reason are true but reason is not the correct explanation of assertion

• If assertion is true but reason is false

• If both assertion and reason are false

253.

A nucleus of mass number A, originally at rest, emits on  $\mathrm{\alpha }$-particle with speed v. The daughter nucleus recoil with speed a speed 

• $\frac{2\mathrm{v}}{\mathrm{A} + 4}$

• $\frac{4\mathrm{v}}{\mathrm{A} + 4}$

• $\frac{4\mathrm{v}}{\mathrm{A} - 4}$

• $\frac{2\mathrm{v}}{\mathrm{A} - 4}$

When an electron-positron pair annihilates, the energy released is about

• 0.8 × 10^-13 J

• 1.6 × 10^-13 J

• 3.2 × 10^-13 J

• 4.8 × 10^-13 J

Two parallel beams of positrons moving in the same direction will

• repel each other

• will not interact with each other

• attract each other

• be deflected normal to the plane containing the two beams

Carbon dating is best suited for determining the age of fossils if their age in years is of the order of

• 10⁸

• 10⁴

• 10⁴

• 10⁶

The dependence of binding energy per nucleon, B_A  on the mass number A, is represented by

Assertion:  ⁹⁰Sr from the radioactive fall out from a nuclear bomb ends up in the bones of human beings through the milk consumed by them. It causes impairment of the production of red blood cells.

Reason: The energies β-particles emitted in the decay of ⁹⁰Sr damage the bone marrow.

• If both assertion and reason are true and reason is the correct explanation of assertion

• If both assertion and reason are but reason is not the correct explanation of assertion  

• If asserion and reason is false

• If both assertion and reason are false

Assertion: Energy is released in nuclear fission.

Reason: Total binding energy of the fission fragments is larger than the total binding energy of the parent nucleus.

• If both assertion and reason are true and reason is the correct explanation of assertion

• If both assertion and reason are true but reason is not the correct explanation of assertion

• If assertion is true but reason is false

• If both assertion and reason is false

Assertion:  Heavy water preferred ever ordinary water as a moderator in reactors. 

Reason:  Heavy water, used for slowing down the neutrons, has lesser absorption probability
of neutrons than ordinary water.

• If both assertion and reason are true and reason is the correct explanation of assertion

• If both assertion and reason are true but reason is not the correct explanation of assertion

• If assertion is true but reason is false

• If both assertion and reason are false