Question

One atomic mass unit is $\frac{1}{12}$ times the mass of one atom of .

• A. carbon-12
• B. nitrogen-12
• C. boron-12

Answer 1

The correct option is A carbon-12

Atomic mass of an element is measured in terms of unified atomic mass units (u) or daltons (Da).

The carbon-12 atom is taken as the standard reference and the masses of all other atoms are measured relative to it.

1 u or 1 Da is taking one atom of carbon-12 and chopping it up into 12 equal parts and weighing 1 of these parts. This is why the definition says $\frac{1}{12}$ times the mass of one atom of carbon-12.