Question

$1amu=\frac{1}{12}$ the mass of one:

• A. $C-12$ atom
  
• B. $N$ atom
  
• C. $O$ atom
  
• D. $H$ atom
  

Answer 1

Answer: (A)

$C-12$ atom

An atomic mass unit (symbolized amu) is defined as precisely 1/12 the mass of an atom of carbon-12. The carbon-12 ($C-12$) atom has six protons and six neutrons in its nucleus. In imprecise terms, one amu is the average of the proton rest mass and the neutron rest mass.

Hence, the correct option is $\text{A}$