What is the mass of 0.80 moles of Mg?

You calculate the mass (m) by multiplying the molar mass (M) with the moles (n). Molar mass (M) is found in the the periodic table.

m=n*M

n=m/M

M=m/n

n=0.80moles

M=24.3050 g/moles

m=0.80moles*24.3050 g/moles = 19.444 g

Here is the question with its answers:

What is the mass of 0.80 moles of Mg?

7.5 * 1023 grams

4.8 * 1023 grams

30 grams

19 grams

The correct answer is D) 19 grams