Question:
Assertion (A): One atomic mass unit is defined as one-twelfth of the mass of
one carbon-12 atom.
Reason (R): Carbon-12 isotope is the most abundant isotope of carbon
and has been chosen as the standard.
(i) Both A and R are true and R is the correct explanation of A.
(ii) Both A and R are true but R is not the correct explanation of A.
(iii) A is true but R is false.
(iv) Both A and R are false.
Solution:
Option (ii) is correct. Carbon-12 is considered a standard for defining the atomic and molecular mass.