To determine which option contains the largest number of molecules, we need to calculate the number of molecules in each option given, using the concept of moles and Avogadro's number.
### Step-by-Step Solution:
1. **Understand the Concept of Moles**:
- A mole is a unit that measures the amount of substance. One mole contains \(6.022 \times 10^{23}\) entities (molecules, atoms, etc.), known as Avogadro's number.
2. **Calculate the Number of Molecules for Each Option**:
- For each substance, we will calculate the number of moles and then convert that to the number of molecules using Avogadro's number.
3. **Example Calculation**:
- If we have 0.2 moles of H2M:
\[
\text{Number of molecules} = 0.2 \, \text{moles} \times 6.022 \times 10^{23} \, \text{molecules/mole} = 1.2044 \times 10^{23} \, \text{molecules}
\]
- For 4 moles of H2M:
\[
\text{Number of molecules} = 4 \, \text{moles} \times 6.022 \times 10^{23} \, \text{molecules/mole} = 2.4088 \times 10^{24} \, \text{molecules}
\]
- For 17 grams of H2O (molar mass = 18 g/mol):
\[
\text{Number of moles} = \frac{17 \, \text{g}}{18 \, \text{g/mol}} \approx 0.9444 \, \text{moles}
\]
\[
\text{Number of molecules} = 0.9444 \, \text{moles} \times 6.022 \times 10^{23} \, \text{molecules/mole} \approx 5.68 \times 10^{23} \, \text{molecules}
\]
- For 16 grams of CO2 (molar mass = 44 g/mol):
\[
\text{Number of moles} = \frac{16 \, \text{g}}{44 \, \text{g/mol}} \approx 0.3636 \, \text{moles}
\]
\[
\text{Number of molecules} = 0.3636 \, \text{moles} \times 6.022 \times 10^{23} \, \text{molecules/mole} \approx 2.19 \times 10^{23} \, \text{molecules}
\]
4. **Compare the Results**:
- H2M (0.2 moles): \(1.2044 \times 10^{23}\) molecules
- H2M (4 moles): \(2.4088 \times 10^{24}\) molecules
- H2O (17 grams): \(5.68 \times 10^{23}\) molecules
- CO2 (16 grams): \(2.19 \times 10^{23}\) molecules
5. **Conclusion**:
- The substance with the largest number of molecules is **4 moles of H2M**, which contains \(2.4088 \times 10^{24}\) molecules.
