The largest number of molecules in

Options

A. `36 g` of water
B. `28 g` of carbon monoxide
C. `46 g` of ethly alcohol
D. `54 g` of nitrogen pentoxide

Explanation

To find the largest number of molecules in the given substances, we will calculate the number of moles for each substance and then convert that to the number of molecules using Avogadro's number (6.022 x 10²³ molecules/mole).

### Step-by-Step Solution:

1. **Calculate the number of moles of water (H₂O):**
- Given mass = 36 grams
- Molar mass of water (H₂O) = 18 g/mol
- Number of moles = mass / molar mass = 36 g / 18 g/mol = 2 moles

2. **Calculate the number of moles of carbon monoxide (CO):**
- Given mass = 28 grams
- Molar mass of carbon monoxide (CO) = 28 g/mol
- Number of moles = mass / molar mass = 28 g / 28 g/mol = 1 mole

3. **Calculate the number of moles of ethyl alcohol (C₂H₅OH):**
- Given mass = 46 grams
- Molar mass of ethyl alcohol (C₂H₅OH) = 46 g/mol
- Number of moles = mass / molar mass = 46 g / 46 g/mol = 1 mole

4. **Calculate the number of moles of nitrogen pentoxide (N₂O₅):**
- Given mass = 54 grams
- Molar mass of nitrogen pentoxide (N₂O₅) = 108 g/mol (calculated as 28 g/mol for N₂ + 80 g/mol for O₅)
- Number of moles = mass / molar mass = 54 g / 108 g/mol = 0.5 moles

5. **Convert the number of moles to the number of molecules:**
- For water: 2 moles × 6.022 x 10²³ molecules/mole = 1.2044 x 10²⁴ molecules
- For carbon monoxide: 1 mole × 6.022 x 10²³ molecules/mole = 6.022 x 10²³ molecules
- For ethyl alcohol: 1 mole × 6.022 x 10²³ molecules/mole = 6.022 x 10²³ molecules
- For nitrogen pentoxide: 0.5 moles × 6.022 x 10²³ molecules/mole = 3.011 x 10²³ molecules

6. **Compare the number of molecules:**
- Water: 1.2044 x 10²⁴ molecules
- Carbon monoxide: 6.022 x 10²³ molecules
- Ethyl alcohol: 6.022 x 10²³ molecules
- Nitrogen pentoxide: 3.011 x 10²³ molecules

7. **Conclusion:**
- The largest number of molecules is in water (H₂O) with 1.2044 x 10²⁴ molecules.

### Final Answer:
The largest number of molecules is in **36 grams of water (H₂O)**.