physical science
posted by Lisa .
how much sugar is dissolved in 500 grams of a solution if the solution is 70 percent sugar by mass?
Also,
What is the concentration of a solution that contains 45 grams of sugar in 500 grams of solution?
thank you

70% of 500 g, since the 500 g "solution" is the sum of both sugar and water.

For the second problem,
[mass sugar/mass solution]*100 = percent by mass. 
Thank you DrBob222 for your kind help !! :)

. A solution contains 45 grams of nitrogen(N2) gas and 40 grams of argon(Ar). What is the mole fraction of argon in this solution?