The total number of electrons present in 18 mL of water (density of water is `1 g mL^(-1)` is:

Options

A. `6.02 xx 10^(23)`
B. `6.02 xx 10^(22)`
C. `6.02 xx 10^(24)`
D. `6.02 xx 10^(25)`

Explanation

To find the total number of electrons present in 18 mL of water, we can follow these steps:

### Step 1: Calculate the mass of water
Given:
- Volume of water = 18 mL
- Density of water = 1 g/mL

Using the formula:
\[ \text{Mass} = \text{Volume} \times \text{Density} \]
\[ \text{Mass of water} = 18 \, \text{mL} \times 1 \, \text{g/mL} = 18 \, \text{g} \]

### Step 2: Calculate the number of moles of water
The molecular weight of water (H₂O) is approximately 18 g/mol.

Using the formula:
\[ \text{Number of moles} = \frac{\text{mass}}{\text{molecular weight}} \]
\[ \text{Number of moles of H₂O} = \frac{18 \, \text{g}}{18 \, \text{g/mol}} = 1 \, \text{mol} \]

### Step 3: Calculate the number of molecules of water
Using Avogadro's number (Nₐ = \(6.02 \times 10^{23}\) molecules/mol):
\[ \text{Number of molecules of H₂O} = \text{Number of moles} \times Nₐ \]
\[ \text{Number of molecules of H₂O} = 1 \, \text{mol} \times 6.02 \times 10^{23} \, \text{molecules/mol} = 6.02 \times 10^{23} \, \text{molecules} \]

### Step 4: Calculate the total number of electrons in water
Each water molecule (H₂O) contains:
- 1 oxygen atom (8 electrons)
- 2 hydrogen atoms (1 electron each, total 2 electrons)

Total electrons per water molecule:
\[ \text{Total electrons in 1 H₂O} = 8 + 2 = 10 \, \text{electrons} \]

Now, calculate the total number of electrons:
\[ \text{Total number of electrons} = \text{Number of molecules} \times \text{Electrons per molecule} \]
\[ \text{Total number of electrons} = 6.02 \times 10^{23} \, \text{molecules} \times 10 \, \text{electrons/molecule} = 6.02 \times 10^{24} \, \text{electrons} \]

### Final Answer:
The total number of electrons present in 18 mL of water is \(6.02 \times 10^{24}\) electrons.

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