Lakshmi has a sample of ammonium nitrate (NH. NO3) that has a mass of 40.10 g. She knows that the molar mass of NH. NO3 is 80.0432 g/mol. To the correct number of significant digits, how many moles of NH. NO3 does the sample contain?
0.50
0.500979
0.500980
0.5010

0.500979

Explanation:

To determine the number of moles, take a look at the following formula and substitute known values -

Moles = Mass / Molar Mass,

Moles = 40.10 grams / 80.0432 grams / mole

as you can see, 40.10 / 80.0432 = ( About ) 0.500979, which is option B

Hope that helps!