Acylinder of lead has a radius of 4.0cm and a height of 10.0cm. what is the mass of the cylinder of lead?

Explanation:

So lead has a density of 11.34 g/cm^3 according to a quick google search.  If this is not the value you are using, just replace what you do use where I put 11.34

knowing the density, if we knew the volume we could find the mass by unit conversion since g/cm^3 * cm^3 = g, so we would multiply the density by the volume.  And the question gives us the means to find the volume.

Volume of a cylinder is area of its base times the height.  Area of its base, a circle (since it's a cylinder) is π*r^2 where r is the radius and π is roughly 3.14.  I will leave π as the symbol until the end so it's easier to deal with.

So volume = area * height = πr^2*h = π4^2*10 = 160π (I moved pi to the back).  It's units are cm^3 since both measurements were in cm.  You can feel free to multiply π by 160 now if you like.  Anyway, now that we have the volume we multiply it by the density.  so 160π cm^3 * 11.34 g/cm^3 = 1814.4π g.  If you multiply that by 3.14 for π you get 5697.216 g.  And there's the mass.  Let em know if there was something you didn't understand.  

elements make up everything, and they combine to make compounds.

the answer is c