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): Dobereiner's triads were applicable to all known elements without any exception. Reason (R): In Dobereiner's triads, the atomic weight of the middle element was roughly the average of the atomic weights of the first and third elements. 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.