How many oxygen atoms are there in 0.25 mole of CO₂?

Question

Quizplus · Accepted Answer

First, we need to determine the number of oxygen atoms in one molecule of COS (carbonyl sulfide). There is one oxygen atom in the molecule, so there is one oxygen atom in one mole of COS (the molar mass of COS is 60.07 g/mol). 
Then, we can use the following formula:
Number of atoms/molecules = (Avogadro's number) x (number of moles)
Number of oxygen atoms in 0.25 mole of COS = (6.022 x 10^23 atoms/mol) x (0.25 mol)
Number of oxygen atoms in 0.25 mole of COS = 1.506 x 10^23, which can be expressed in scientific notation as 1.5 x 10^23. Therefore, the answer is C.

How Many Oxygen Atoms Are There in 0