The mass of a mole of electrons is: 0.008 g 0.184 g 0.55 mg 1.673

Options

A. 0.008 g
B. 0.184 g
C. 0.55 mg
D. 1.673

Explanation

To find the mass of a mole of electrons, we can follow these steps:

### Step 1: Determine the mass of a single electron.
The mass of an electron is given as:
\[ m_e = 9.1 \times 10^{-31} \text{ kg} \]
or
\[ m_e = 9.1 \times 10^{-28} \text{ g} \]

### Step 2: Use Avogadro's number to find the mass of one mole of electrons.
Avogadro's number (\(N_A\)) is:
\[ N_A = 6.022 \times 10^{23} \text{ electrons/mole} \]

### Step 3: Calculate the mass of one mole of electrons.
The mass of one mole of electrons can be calculated using the formula:
\[ \text{Mass of 1 mole of electrons} = N_A \times m_e \]
Substituting the values:
\[ \text{Mass of 1 mole of electrons} = 6.022 \times 10^{23} \times 9.1 \times 10^{-28} \text{ g} \]

### Step 4: Perform the multiplication.
Calculating the above expression:
\[ \text{Mass of 1 mole of electrons} = 6.022 \times 9.1 \times 10^{-5} \text{ g} \]
Calculating \(6.022 \times 9.1\):
\[ 6.022 \times 9.1 = 54.8 \]
Thus:
\[ \text{Mass of 1 mole of electrons} = 54.8 \times 10^{-5} \text{ g} \]

### Step 5: Convert grams to milligrams.
Since \(1 \text{ mg} = 10^{-3} \text{ g}\), we convert grams to milligrams:
\[ 54.8 \times 10^{-5} \text{ g} = \frac{54.8 \times 10^{-5}}{10^{-3}} \text{ mg} \]
This simplifies to:
\[ 54.8 \times 10^{-2} \text{ mg} = 0.548 \text{ mg} \]

### Step 6: Round the answer.
Rounding \(0.548 \text{ mg}\) gives us:
\[ \text{Mass of 1 mole of electrons} \approx 0.55 \text{ mg} \]

### Final Answer:
The mass of a mole of electrons is **0.55 mg**.

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