Chemistry
posted by Shelby on .
The density of dry air measured at 25 degrees Celsius is 1.19x10 to the negative 3rd power. What is the volume of 50.0g of air?

mass = volume x density.
Substitute for mass and density; solve for volume. Make sure the units of density (you don't list that) agrees with the unit you want in the answer. 
can u explain that a little more because i still don't understand

There isn't anything to explain.
mass = volume x density. That's the formula. That's it. End of story. You read the problem, substitute the numbers, solve the equation.
mass in the problem = 50g
density in the problem = 1.19E3. You don't list the units. I will assume for purposes of showing you that this is 1.18E3 g/mL. If it is some other unit you will need to adjust that.
Substitute.
mass = volume x density
50 = volume(in mL) x 1.19E3 g/mL
volume = 50/1.19E3 = about 42000 mL.
If you will explain what trouble you are having perhaps I can focus on a better answer. 
50/.00119=42016.8067227mL>>then you have to round to 2 significant digits b/c 50 has 2 sig figs which is the least # of sig figs

50/.00119=42016.8067227mL>>then you have to round to 2 significant digits b/c 50 has 2 sig figs which is the least # of sig figs, so its 42,000mL

sma