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): Isotopes of an element have essentially identical chemical properties. Reason (R): Chemical properties are primarily controlled by the number of valence electrons and nuclear mass. In the light of the above statements, choose the correct answer from the options given below:

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