Compared to the mass of lightest nuclei, the mass of an electron is only-

Options

A. `1//80`
B. `1//800`
C. `1//1836`
D. `1//2800`

Explanation

To solve the problem of comparing the mass of an electron to the mass of the lightest nucleus (hydrogen), we can follow these steps:

### Step 1: Identify the mass of the lightest nucleus
The lightest nucleus is that of hydrogen, which consists of one proton. The mass of a hydrogen atom (which is approximately equal to the mass of its nucleus) is given as:
- Mass of hydrogen nucleus (H) = \(1.67 \times 10^{-27}\) grams.

### Step 2: Identify the mass of an electron
The mass of an electron is given as:
- Mass of electron (e) = \(9.11 \times 10^{-31}\) kg.

### Step 3: Convert the mass of the electron to grams
Since the mass of hydrogen is given in grams, we need to convert the mass of the electron from kilograms to grams:
- \(9.11 \times 10^{-31} \text{ kg} = 9.11 \times 10^{-31} \times 10^3 \text{ g} = 9.11 \times 10^{-28} \text{ g}\).

### Step 4: Calculate the ratio of the mass of the electron to the mass of the hydrogen nucleus
Now we can find the ratio of the mass of the electron to the mass of the hydrogen nucleus:
\[ \text{Ratio} = \frac{\text{Mass of electron}}{\text{Mass of hydrogen nucleus}} = \frac{9.11 \times 10^{-28} \text{ g}}{1.67 \times 10^{-27} \text{ g}}. \]

### Step 5: Perform the calculation
Calculating the ratio:
\[ \text{Ratio} = \frac{9.11}{1.67} \times \frac{10^{-28}}{10^{-27}} = \frac{9.11}{1.67} \times 10^{-1} \approx 0.545 \times 10^{-1} = 0.0545. \]

### Step 6: Express the ratio in terms of a fraction
To express this ratio in simpler terms, we can find the approximate fraction:
\[ \text{Ratio} \approx \frac{1}{1840}. \]

### Conclusion
Thus, compared to the mass of the lightest nucleus (hydrogen), the mass of an electron is only approximately \( \frac{1}{1840} \) of the mass of hydrogen.

### Final Answer
The mass of an electron is only \( \frac{1}{1840} \) of the mass of the lightest nucleus (hydrogen).

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