Assertion:Nuclear binding energy per nucleon is in the order -`""_(4)^9Be gt ""_(3)^(7)Li gt ""_(2)^(4)He`.
Reason:Binding energy per nucleon increases linearly with difference in number of neutrons and protons.

Options

A. If both assertion and reason are true and reason is the explaination of assertion.
B. If both assertion and reason are true but reason is not the correct explaination of assertion
C. If assertion is true but reason is false
D. If both assertion and reason are false.

Answer

D

Explanation

Binding energy per nucleon of`""_(3)Li^(7)` (5.38 MeV) is lesser than `""_(2)He^(4)`(7.08 MeV)` as helium is found to be more stable than Li.As the atomic mass number increases,the bionding energy per nucleon decreases.As increases,the binding energy per nucleon decreases.As the atomic number and the atomic mass number increase,the repulsive electrostatic forces within the nucleus increase due to the freater number of protons in the heavy elements.To overcome this increased repulsion,the proportion of neutrons in the nucleus must increase to maintain stability.This increase in the neutron-to-proton ration only partially compensates for the growing proton-protom repulsive force in the heavier,naturally occurring elements.Because the repulsive forces are increasing,less energy must be supplied,on the average,to remove a nucleon from the nucleus.The BE/A has decreased.The BE/A of a nucleous is an indication of its degree of stability.Generally,the more stable nuclides have higher BE/A than the less stable ones.The increase in BE/A as the atomic mass n umber decreases from 260 to 60 is the primary reason for the energy liberation in the fission process.The increase in the BE/A as the atomic mass number increases from 1 to 60 is the reason for the energy liberation in the fusion process,Which is the opposite reaction of fission.