Final answer:
A hydrogen atom is smaller than a carbon atom, with a mass of 1.674 x 10^-24 grams per atom compared to carbon's mass of 1.995 x 10^-23 grams per atom. Therefore, the correct answer is option B, Hydrogen atom.
Step-by-step explanation:
When looking at the masses of carbon and hydrogen atoms, it is clear that the mass of a hydrogen atom is smaller than that of a carbon atom. Given the masses provided in the question, the mass of a carbon atom is 1.995 x 10-23 grams per atom, and the mass of a hydrogen atom is 1.674 x 10-24 grams per atom. We can see that the exponent for hydrogen (-24) is higher than that for carbon (-23), which means that the mass of a hydrogen atom is indeed smaller because the base numerical value, 1.674 (for hydrogen), is multiplied by a much smaller number (10-24) compared to 1.995 (for carbon) multiplied by 10-23.
To compare the two numbers more easily, we might also look at the atomic mass unit (amu) relative to carbon-12, which has an atomic mass of exactly 12 amu. Hydrogen has an atomic mass of approximately 1 amu. Thus, the answer to the question is that a hydrogen atom is smaller than a carbon atom, making option B (Hydrogen atom) the correct choice.