Chemistry · Classification of Elements and Periodicity in Properties

Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A): Helium is placed in Group 18 along with other noble gases despite having an electronic configuration of \( 1s^2 \). Reason (R): Helium has a completely filled valence shell (\( 1s^2 \)) and exhibits properties characteristic of other noble gases. In the light of the above statements, choose the correct answer from the options given below:

1. A
   Both (A) and (R) are true and (R) is the correct explanation of (A).
2. B
   Both (A) and (R) are true but (R) is NOT the correct explanation of (A).
3. C
   (A) is true but (R) is false.
4. D
   (A) is false but (R) is true.