Question

You have one mole of each of these atoms: carbon-12, oxygen-16, and uranium-235. Which substance has more atoms?

1) oxygen-18
2) carbon-12
3) uranium-235
4) all have the same number of atoms

Answer 1

One mole of any substance, including carbon-12, oxygen-18, and uranium-235, contains exactly the same number of atoms, which is Avogadro's number of 6.022 × 10^23. Therefore, all these substances have the same number of atoms when measured in moles.

Step-by-step explanation:

The concept of a mole is a fundamental component in chemistry that represents Avogadro's number, which is 6.022 × 1023 particles of a substance. Regardless of the element or isotope, one mole of any substance contains the same number of atoms. When you have one mole of carbon-12 (12C), oxygen-16 (16O), or uranium-235 (235U), each sample contains 6.022 × 1023 atoms of that respective element. Hence, whether it's oxygen-18, carbon-12, or uranium-235, one mole of each will always have the same number of atoms: 6.022 × 1023 atoms. Therefore, all the given substances have the same number of atoms when you have one mole of each, so the correct answer is 4) all have the same number of atoms.