Chemistry · Some Basic Concepts of Chemistry

Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A): The atomic mass of an element is expressed relative to \( ^{12}\text{C} \) isotope of carbon. Reason (R): \( ^{12}\text{C} \) isotope was assigned a mass of exactly \( 12\text{ atomic mass units (u)} \) by IUPAC. 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.