Chemistry
posted by Vy .
A lead atom has a mass of 3.40×10−22 g. How many lead atoms are in a cube of lead that has a volume of 1.40 cm^3 if the density of lead is 11.3 g/cm^3?

Is the mass of the lead 3.4 x 10^(22)
or literally 3.4 x 10  22 or just 22g?
The problem has given you volume and density.
D = mass/ volume
You're trying to find mass, so your equation's going to be m= dv
m= 15. 82 g
Divide this by whatever your mass was, either 3.4 x 10^(22)
or 3.4 x 10  22 or just 22g.
That number will be the number of lead atoms in the cube. 
4.6 x 10^22