The atomic masses of two isotopes of chlorine are 35 and 37. The number of neutrons respectively will be

Options

A. 18, 20
B. 20,18
C. 17, 18
D. 18,17

Explanation

To find the number of neutrons in the isotopes of chlorine with atomic masses 35 and 37, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Atomic Number of Chlorine**:
- The atomic number of chlorine (Cl) is 17. This means that chlorine has 17 protons.

2. **Understand the Concept of Isotopes**:
- Isotopes are variants of the same element that have the same number of protons (atomic number) but different mass numbers due to a different number of neutrons.

3. **Calculate the Number of Neutrons for Chlorine-35**:
- The mass number of the first isotope (Chlorine-35) is 35.
- To find the number of neutrons, use the formula:
\[ \text{Number of Neutrons} = \text{Mass Number} - \text{Atomic Number} \]
- Substituting the values:
\[ \text{Number of Neutrons} = 35 - 17 = 18 \]

4. **Calculate the Number of Neutrons for Chlorine-37**:
- The mass number of the second isotope (Chlorine-37) is 37.
- Again, use the same formula:
\[ \text{Number of Neutrons} = \text{Mass Number} - \text{Atomic Number} \]
- Substituting the values:
\[ \text{Number of Neutrons} = 37 - 17 = 20 \]

5. **Summarize the Results**:
- For Chlorine-35, the number of neutrons is 18.
- For Chlorine-37, the number of neutrons is 20.

### Final Answer:
- The number of neutrons in Chlorine-35 is 18, and in Chlorine-37 is 20.

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