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