2 Answers

To work out the mass of 9.44 x 10^24 molecules of NO2 and being given its molar mass of 46.01g/mol you have to use this formula which is
n=N/NA
n=number of moles
N=molecules of substance
NA=avogadro’s number which is 6.02 x 10^23
n=(9.44 x 10^24)/(6.02 x 10^23)=15.68
then to work out its mass you use this formula
m=n x M
m=mass
n=number of moles
M=molar mass
m=15.68 x 46.01= 721.44g
so the mass of 9.44 x 10^24 molecules of NO2 is 721.44g if you want to convert it into kilograms divide it by 1000 or 10^3 but the standard unit for mass is grams.
Hope this answers your question=)

A molar mass of 46.01g means that every mole of NO2 molecules (6.02 x 10^23 molecules) weighs 46.01g
So, divide 9.44 x 10^24 by 6.02 x10^23 to find how many moles of NO2 you have, then multiply this by the molar mass (46.01g)
This should come out to 721.49g, or 0.721kg