42.035 g of carbon contains how many moles of carbon?

3.5 mole of carbon

Explanation:

The atomic mass of carbon is 12.011 grams per mole.

That means, every mole of carbon atoms has a mass of 12.011 grams.

If you have 42.035 grams of carbon atoms, then every 12.011 grams of those carbon atoms, is 1 mole of carbon atoms ...

You can solve this using unit conversion:

# mole carbon atoms = 42.035 grams C x (1 mole C / 12.011 g C) = 3.5 mole C