Question

Which one of the following will have the largest number of atoms?

• A. 1 g Au (s)
• B. 1 g Na (s)
• C. 1 g Li (s)
• D. 1 g of Cl₂ (g)

Answer 1

The Correct Option is C

To determine which substance contains the largest number of atoms given equal masses, we need to consider the concept of moles and the molar mass of each substance. The number of atoms in a sample can be determined using Avogadro's number, which is 6.022 \times 10^{23} atoms per mole.

First, calculate the number of moles for each substance using the formula:

\text{Number of Moles} = \frac{\text{Mass}}{\text{Molar Mass}}

1. 1 g of Au (gold):

   The molar mass of Au is approximately 197 \, \text{g/mol}. Therefore,

   \text{Number of Moles of Au} = \frac{1}{197} \approx 0.00508 \, \text{moles}

2. 1 g of Na (sodium):

   The molar mass of Na is approximately 23 \, \text{g/mol}. Therefore,

   \text{Number of Moles of Na} = \frac{1}{23} \approx 0.04348 \, \text{moles}

3. 1 g of Li (lithium):

   The molar mass of Li is approximately 6.94 \, \text{g/mol}. Therefore,

   \text{Number of Moles of Li} = \frac{1}{6.94} \approx 0.14409 \, \text{moles}

4. 1 g of Cl₂ (chlorine gas):

   The molar mass of Cl₂ is approximately 71 \, \text{g/mol}. Therefore,

   \text{Number of Moles of Cl}_2 = \frac{1}{71} \approx 0.01408 \, \text{moles}

Comparing the moles calculated above, we find that 1 g of lithium has the largest number of moles. Since the number of atoms is directly proportional to the number of moles, 1 g of lithium will have the largest number of atoms.

Thus, the correct answer is 1 g Li (s), which contains the largest number of atoms.