Problem page a virus has a mass of ×9.010−12mg and an oil tanker has a mass of ×3.0107kg . use this information to answer the questions below. be sure your answers have the correct number of significant digits. what is the mass of 1 mole of viruses? g how many moles of viruses have a mass equal to the mass of an oil tanker? ×10

A. The mass of one mole of the virus is calculated by multiplying the mass of a single virus by the Avogadro's number which is equal to 6.022 x 10^23. Performing this operation,

   mass = (9.0 x 10^-12 mg)(6.022 x 10^23) = 5.42 x 10^12 mg

In correct number of significant figures, the answer would only have to be 5.4 x 10^12 mg. 

b. The number of moles of the virus that will have the same mass as the oil tanker is calculated by dividing the mass of the oil tanker by the mass of one mole of the virus. Note that doing division, both would have to have the same units. 

       n = (3.0 x 10^7 kg) / (5.4 x 10^12 mg)(1 g/1000 mg)(1 kg/1000 g)

Simplifying,
               n = 6

In correct number of significant figures, the answer is 6.0.