Question

Assertion : The emission of $\alpha -particles$ results in the formation of isodiaphere of parent element.
Reason : Isodiaphers have same isotopic number.

• A. If both (A) and (R) are correct, and (R) is the correct explanation of (A).
• B. If both (A) and (R) are correct, but (R) is not the correct explanation of (A).
• C. If (A) is correct, but (R) is incorrect.
• D. If (A) is incorrect, but (R) is correct.
• E. If both (A) and (R) are incorrect.

Answer 1

The correct option is B If both (A) and (R) are correct, but (R) is not the correct explanation of (A).

Assertion: The emission of $\alpha -particles$ results in the formation of isodiaphere of the parent element. An alpha particle contains 2 neutrons and 2 protons. When an alpha particle is lost, the daughter element has 2 proton less and 2 neutrons less than the parent nucleus. Hence, the $N-Z$ (difference in the number of neutrons and the number of protons) of the daughter nucleus is same as that of the parent nucleus.
Reason: Isodiaphers have the same isotopic number. The isotopic number is the difference in the number of neutrons and the number of protons.
Thus both $\left(A\right)$ and $\left(R\right)$ are correct, but $\left(R\right)$ is not the correct explanation of $\left(A\right)$.