Part a how many carbon atoms are in a 2-carat pure diamond that has a mass of 0.40 g. express your answer using two significant figures.

We have to calculate the number of carbon atoms present in 2-carat pure diamond.

The number of carbon atoms present in 2-carat pure diamond is: 0.19 X 10²³ number of carbon atom.

Diamond is one allotrope of carbon. Atomic mass of carbon is 12.

Mass of one mole carbon atom is 12 g. One mole carbon contains Avogadro's number i. e, 6.023 X 10²³ number of atoms.

0.40 g diamond contains 0.40/12 moles = 0.033 moles of carbon atom.

So, number of carbon atoms present in 0.40 g diamond (i. e, 0.033 mole diamond) is 0.033 X 6.023 X 10²³ = 1.98 X 10²²=0.19 X 10²³.

Therefore, 0.19 X 10²³ number of carbon atoms are in a 2-carat pure diamond that has a mass of 0.40 g