Assertion (A) : The isotopes are the atoms of the same element with different atomic masses. They require different positions in the periodic table.
Reason (R) : Variable number of neutrons in the nuclei of the atoms of same elements leads to the different atomic masses.

Options

A. Both A and R true and R is the correct explanation of A
B. Both A and R are true but R is not a correct explanation of A
C. A is true but R is false
D. A is false but R is true

Answer

D