1 mole of which of the following substances contains the largest number of atoms?

• A. NaCl
• B. H2O
• C. CO2
• D. C2H6

Answer: (D)

Verified step by step guidance

1. Understand that 1 mole of any substance contains Avogadro's number of formula units (6.022 \times 10^{23}), but the number of atoms per formula unit varies depending on the compound.
2. Determine the number of atoms in one formula unit of each substance by adding the atoms of each element: for example, NaCl has 1 Na and 1 Cl atom, so 2 atoms total per formula unit.
3. Calculate the total number of atoms per formula unit for each compound: H2O has 2 H + 1 O = 3 atoms; CO2 has 1 C + 2 O = 3 atoms; C2H6 has 2 C + 6 H = 8 atoms.
4. Since 1 mole contains Avogadro's number of formula units, multiply the number of atoms per formula unit by Avogadro's number to find the total atoms in 1 mole of each substance.
5. Compare the total atoms for each substance; the compound with the highest number of atoms per formula unit will have the largest number of atoms in 1 mole.