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)…

Question

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:

1. A. A, B, and C only
2. B. A, B, and D only (Correct answer)
3. C. B, C, and D only
4. D. B, D, and E only

Correct Answer

Option B — A, B, and D only

Detailed Solution & Explanation

The correct answer is A, B, and D only.

Key Points

• Number of atoms $=\dfrac{\text{given mass}}{\text{molar mass}}\times(\text{atomicity})\times N_A$.
• A: $\dfrac{212}{106}\times6=12N_A$; B: $\dfrac{248}{62}\times3=12N_A$; D: $\dfrac{12}{2}\times2=12N_A$ — all equal to $12N_A$.
• C: $\dfrac{240}{40}\times3=18N_A$ and E: $\dfrac{220}{44}\times3=15N_A$ differ.
• Hence A, B and D have the same number of atoms.