Avirus has a mass of ×9.010−12mg and an oil tanker has a mass of ×3.0107kg . what is the mass of one mole of viruses?

Avogadro's number is just a constant and without units. It is alike to a dozen or a gross, only much bigger. 1 mole means that the number of particles existing is 6.022×10²³.

If 1 virus has a mass of 9.0×10^-12 mg, then 10 viruses would have a mass of (9.0 × 10^-12) × 10 = 9.0 × 10^ -11 mg. Likewise, a mole of viruses will have a mass of (9.0 × 10^-12) (6.022×10²³) = 5,419,800,000,000 mg = 5.4 × 10^6 kg, correct to 2 significant figures. 

the correct option is:

b. a value of the variable that makes the polynomial equal to zero.

the root or roots of a polynomial are the values of the variable that makes the polynomial equal to 0. we can find the roots of a polynomial making the expression equal to 0 and then, isolating the variable (it it has just one variable).

for example, given the following polynomial:

the root or zero of the polynomial, can be found by making the expression equal to 0, and then, isolating the variable, so, finding the root we have:

therefore, we have that the root of the polynomial is equal to 2.

we must remember that the number of roots that a polynomial can have, will depend on the degree of the polynomial, a first degree polynomial have will have one single root, a second degree polynomial (quadratic expression) may have two roots and so.

hence the correct option is:

b. a value of the variable that makes the polynomial equal to zero.

have a nice day!