Assertion(A) One atomic mass unit is defined as one twelth 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 standard.

Options

A. If both assertion and reason are true and reason is the correct explanation of assertion
B. If both assertion and reason are true but reason is not correct explanation of assertion.
C. If assertion is true but reason is false.
D. If both assertion and reason are false.

Explanation

To analyze the given question regarding the assertion and reason, we will break it down step by step.

### Step 1: Understanding the Assertion
The assertion states that "One atomic mass unit is defined as one twelfth of the mass of one carbon-12 atom."

- **Definition of Atomic Mass Unit (AMU)**: The atomic mass unit (AMU) is a standard unit of mass that quantifies mass on an atomic or molecular scale. It is defined as 1/12 the mass of a carbon-12 atom. This means that if you take the mass of a carbon-12 atom and divide it by 12, you will get the value of 1 AMU.

### Step 2: Evaluating the Reason
...