Among the following, choose the ones with equal number of atoms.  
A. 212 g of Na₂CO₃ (s) [molar mass = 106 g]
B. 248 g of Na₂O (s) [molar mass = 62 g]
C. 240 g of NaOH (s) [molar mass = 40 g]
D. 12 g of H₂(g) [molar mass = 2 g]
E. 220 g of CO₂(g) [molar mass = 44 g]
Choose the correct answer from the options given below:

CONCEPT:

Equal Number of Atoms

• The number of atoms in a given sample depends on the number of moles of molecules present, as well as the number of atoms in each molecule.
• The number of moles can be calculated using the formula:

  Moles = Mass / Molar Mass

• Once the moles are determined, the number of molecules can be calculated using Avogadro's number:

  Number of molecules = Moles × 6.022 × 10²³

• To calculate the total number of atoms, multiply the number of molecules by the number of atoms in the molecular formula.

EXPLANATION:

• For each option, calculate the number of moles and the total number of atoms:
  • A. 212 g of Na₂CO₃:
    • Moles = 212 / 106 = 2 moles
    • Na₂CO₃ contains 6 atoms per molecule (2 Na, 1 C, 3 O).
    • Total atoms = 2 × 6 × 6.022 × 10²³ = 72.264 × 10²³ atoms
  • B. 248 g of Na₂O:
    • Moles = 248 / 62 = 4 moles
    • Na₂O contains 3 atoms per molecule (2 Na, 1 O).
    • Total atoms = 4 × 3 × 6.022 × 10²³ = 72.264 × 10²³ atoms
  • C. 240 g of NaOH:
    • Moles = 240 / 40 = 6 moles
    • NaOH contains 3 atoms per molecule (1 Na, 1 O, 1 H).
    • Total atoms = 6 × 3 × 6.022 × 10²³ = 108.396 × 10²³ atoms
  • D. 12 g of H₂:
    • Moles = 12 / 2 = 6 moles
    • H₂ contains 2 atoms per molecule (2 H).
    • Total atoms = 6 × 2 × 6.022 × 10²³ = 72.264 × 10²³ atoms
  • E. 220 g of CO₂:
    • Moles = 220 / 44 = 5 moles
    • CO₂ contains 3 atoms per molecule (1 C, 2 O).
    • Total atoms = 5 × 3 × 6.022 × 10²³ = 90.33 × 10²³ atoms
• Comparing the total atoms A, B, and D have equal total atoms (72.264 × 10²³).

Therefore, the correct answer is Option 2: A, B, and D only.