Question

1 u or 1 amu (atomic mass unit) is equal to ___.

• A. $\left(\frac{1}{16}\right)$${}^{\text{th}}$ of the mass of an atom of oxygen.
• B. $\left(\frac{1}{12}\right)$${}^{\text{th}}$ of the mass of one atom of carbon 12.
• C. 12 carbon atoms.
• D. 16 oxygen atoms.

Answer 1

The correct option is B $\left(\frac{1}{12}\right)$${}^{\text{th}}$ of the mass of one atom of carbon 12.

Carbon -12 isotope is used as the standard reference for measuring atomic masses.
1 atomic mass unit is a mass unit equal to exactly $\left(\frac{1}{12}\right)$${}^{\text{th}}$ the mass of one atom of carbon 12.
It is expressed as u or amu.