Question

One atomic mass unit is equal to
(This question has multiple correct options)
A.) $1.66 \times {10^{ - 27}}g$
B.) $1.66 \times {10^{ - 27}}Kg$
C.) $1.66 \times {10^{ - 27}}mg$
D.) $1.66 \times {10^{ - 24}}g$

Answer 1

In this question, the atomic mass unit is defined as $\dfrac{1}{{12}}th$ of the mass of a carbon atom. Therefore, one atomic mass unit can be calculated by dividing the mass of the carbon atom with twelve ($12$).

Complete step by step answer:
The atomic mass unit is used to express the mass of atomic and subatomic particles. It is also represented as $amu$. One atomic mass unit can be defined as one-twelfth of the mass of carbon-$12$ atom. As we know that the mass of a carbon atom in grams can be given as $1.992 \times {10^{ - 23}}g$. So, from here we can calculate the value of one atomic mass unit.
As we know that,
One atomic mass unit $= \dfrac{1}{{12}}th \times$ (mass of carbon atoms in grams)
Here, mass of carbon atom $= 1.992 \times {10^{ - 23}}g$
Therefore, $1{\text{ amu = }}\dfrac{1}{{12}} \times (1.992 \times {10^{ - 23}}g)$
$1{\text{ amu = 1}}{\text{.66}} \times {\text{1}}{{\text{0}}^{ - 24}}g$
It can also be represented in milligrams by dividing with ${10^3}$. Therefore, we get
$1{\text{ amu = 1}}{\text{.66}} \times {\text{1}}{{\text{0}}^{ - 27}}mg$
Hence, option C.) and D.) are the correct answer.

Additional information: The atomic mass unit can also be expressed as $u{\text{ or Da}}$. Here, $u$ refers to unified atomic mass which is another name for atomic mass units and $Da$ refers to Dalton which is also another name used for atomic mass units. However, $amu$ is also used to express atomic mass units. The atomic mass unit is used to express the atomic masses and molecular masses of the elements or compounds. Some examples of values that are expressed in atomic mass unit are:
The mass of the carbon-$12$ atom in the atomic mass unit is $12u$and the mass of the hydrogen$- 1$ atom in atomic mass unit is $1.007u$

Note:
Always remember that the masses of atoms that we use in calculations (like for oxygen it is $16$, for nitrogen it is $4$,etc.) these all are in atomic mass units that is the mass of any element is given with respect to the mass of carbon.