The molar mass of sucrose is measured to be 342.3 g. The value of Avogadro's number, correct to six significant digits, is 6.022 14 x 1023. The number of molecules in 0.24g of sucrose, written with an appropriate number of significant digits is

A) 4.2 x 1020

B) 4.22 x 1020

C) 4.222 x 1020

D) 4.222 4 x 1020

Avogadro's number represents the number of units in one mole of any substance. This has the value of 6.022 x 10^23 units / mole. This number can be used to convert the number of atoms or molecules into number of moles. We do as follows:

0.24 g (1 mol / 342.3 g) (6.022 x 10^23 molecules / 1 mol) = 4.222 x 10^20 molecules