Question

1. the unified mass unit is defined as

a. the mass of one neutral atom of $\ce{^12c}$
b. $\frac{1}{12}$ of the mass of one neutral atom of $\ce{^12c}$
c. $\frac{1}{6}$ of the mass of one neutral atom of $\ce{^12c}$
d. the mass of the nucleus of $\ce{^12c}$

Explanation:

The unified atomic mass unit is defined relative to the carbon-12 atom, specifically taking 1/12 of the mass of one neutral carbon-12 atom as the standard value.

Answer:

B. $\frac{1}{12}$ of the mass of one neutral atom of $^{12}\text{C}$