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): The atomic number of an element is a more fundamental property than its atomic mass. Reason (R): Moseley showed that a plot of \( \sqrt{\nu} \) of characteristic X-rays emitted from an element against atomic number gives a straight line, whereas atomic mass does not give such a simple linear correlation. 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.