Got this really tricky extra credit question i can't figure out. anyone want to give #24 a try?

The volume of helium in a blimp is 6.28 x 10^9 millimeters. the density of helium in the blimp is .1786 kilogram/meter^3. find the mass of the helium in the blimp.

If 90.0 grams of ethane reacted with excess chlorine, how many grams of dicarbon hexachloride would form

Which of the following are sources of revenue for media companies? a. direct sales to producers b. advertising and subscriptions c. online purchase d. capital investments