Question

Assertion : ${}_{92}{U}^{238}\left(IIIB\right)\stackrel{-\alpha }{\to }A\stackrel{-\alpha }{\to }B\stackrel{-\beta }{\to }C$
Reason : Element B will be of II A group.

• 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 : ${}_{92}{U}^{238}\left(IIIB\right)\stackrel{-\alpha }{\to }A\stackrel{-\alpha }{\to }B\stackrel{-\beta }{\to }C$
When 2 alpha particles are lost, the atomic number decreases by 4 and the mass number decreases by 8. When a beta particle is lost the atomic number increases by 1. Hence, during the given transformation, the atomic number decreases by 1. Hence the group number decreases by 1.
Reason : Element B will be of II A group.
If both (A) and (R) are correct, but (R) is not the correct explanation of (A).