Question

What is the mass of one carbon atom in grams? (Given molar mass of carbon is 12 gram)

Answer 1

A mole of carbon contains $6.022 \times {10^{23}}$ atoms, so a mass of $6.022 \times {10^{23}}$ atoms of carbon is 12 grams. So, we have a large number of atoms and just find the mass of one atom by dividing mass with the number of atoms.

Complete step by step answer:
Given, the mass of one mole of carbon is 12 grams.
We know that a mole is defined as a collection of $6.022 \times {10^{23}}$ atoms.
So, a mole carbon contains $6.022 \times {10^{23}}$ atoms of carbon.
Therefore, we can say that the mass of $6.022 \times {10^{23}}$ atoms of carbon is 12 grams.
So, we have a large number of atoms and just find the mass of one atom by dividing the mass with the number of atoms. Then mass of one atom of carbon is given by
$m = \dfrac{{12}}{{6.022 \times {{10}^{23}}}} = 1.992 \times {10^{ - 23}}gram$
Hence the mass of one carbon atom is $1.992 \times {10^{ - 23}}grams$ and correct answer is option A.

Note:
We mainly use molar masses in calculation and this is not a mass of single but it is mass of one mole of atoms, molecules or ions. We know that in ions and atoms there are only differences in the number of electrons and mass of electrons is negligible. Then the mass of the ion and atom of the same element is the same.