Question 4: Atoms & Nuclei

Question

Assertion : For an element generally $$N \geq Z$$ ( $$N=$$ number of neutrons, $$Z=$$ atomic number)
Reason : Neutrons always experience attractive nuclear force.

Accepted Answer

For an element, it is not always true that number of neutrons $$(N)$$ are greater than or equal to atomic number $$(Z)$$.
For example, in hydrogen atom, there is no neutron but it has one proton.
Therefore, atomic number of hydrogen atom is greater than number of neutrons.
i.e., $$Z>N$$ for hydrogen atom.
The force between neutrons in the nucleus is attractive only upto the range of $$1 \mathrm{~fm}$$, But this attractive force become highly repulsive when neutrons came nearer to about 0.6 to $$0.7 \mathrm{~fm}$$. Therefore, neutrons do not experience always attractive nuclear force.
Hence, both assertion and reason are false.

Answer

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

Answer

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

Answer

If assertion is true, but reason is false.

Answer

If both assertion and reason are false.

Atoms & Nuclei

Assertion : For an element generally $N \geq Z ( N= number of neutrons, Z=$ atomic number) Reason : Neutrons always experience attractive nuclear force.

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