How many grams is 1.2x10^22 particles of sodium carbonate, na2co3

To convert from particles to moles, you need to divide by Avogadro's constant.
To convert from moles to grams, you need to use the molar mass.

1.2*10^22 particles * (1 mole/ 6.022*10^23 particles) * (106 grams/1 mole) = 2.1 g Na₂CO₃

Remember, our final answer will have 2 significant digits because it is limited by the 2 sig figs in 1.2*10^22.

There are 2.1 grams of sodium carbonate in 1.2*10^22 particles of sodium carbonate.

The answer is a) carbon-12