Question

Assertion :The atomic mass of potassium is $39u$. Reason: An atom of potassium is $39$ times heavier than $\frac{1}{12}$th of the mass of carbon atom $\left(C^{12}\right)$.

Read the above assertion and reason and choose the correct option regarding it.

• A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
• B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
• C. Assertion is correct but Reason is incorrect
• D. Assertion is incorrect but Reason is correct

Answer 1

The correct option is A Both Assertion and Reason are correct and Reason is the correct explanation for Assertion

The standard unit for expressing the mass of atom is amu (atomic mass unit).
It is equal to 1/12 of the mass of an atom of carbon -12 equal to $1.6605\times {10}^{-19}g$.
Atomic mass of potassium is 39 u.
An atom of potassium is $39$ times heavier than $\frac{1}{12}$th of the mass of carbon atom $\left(C^{12}\right)$.
Thus, Both Assertion and Reason are correct and Reason is the correct explanation for Assertion