Dark interstellar gas clouds contain so many dust grains that starlight cannot pass through, even though the dust grains are tiny and the spaces between them are quite large by earthly standards. A typical dust grain has a radius of about 10^-7 meter and a mass of about 10^-14 gram.
A. Estimate how many dust particles there are in a cloud containing 1200 Msun of dusty gas, if 0.900% of the cloud's mass is in the form of dust grains.
A. Estimate how many dust particles there are in a cloud containing 1200 Msun of dusty gas, if 0.900% of the cloud's mass is in the form of dust grains.