How many total atoms are present in 3 Na_2SO_4?

• A. 42
• B. 21
• C. 18
• D. 28

Answer: (A)

Verified step by step guidance

1. Identify the chemical formula of the compound: sodium sulfate is represented as \(\mathrm{Na_2SO_4}\).
2. Determine the number of atoms of each element in one formula unit of \(\mathrm{Na_2SO_4}\). There are 2 sodium (Na) atoms, 1 sulfur (S) atom, and 4 oxygen (O) atoms.
3. Calculate the total number of atoms in one formula unit by adding the atoms of all elements: \$2 + 1 + 4$.
4. Since you have 3 formula units of \(\mathrm{Na_2SO_4}\), multiply the total number of atoms in one formula unit by 3: \$3 \times (2 + 1 + 4)$.
5. Sum the values inside the parentheses first, then multiply by 3 to find the total number of atoms in 3 formula units of \(\mathrm{Na_2SO_4}\).