How many electrons, protons and neutrons are present in each of the following ?
`(i) ""_(56)^(137)Ba^(2+) " "(ii) ""_(9)^(19)F^(-) " "(iii) ""_(88)^(226)Ra`.

Answer

To find the number of electrons, protons, and neutrons in the given ions and atoms, we can use the following steps for each part of the question.

### (i) For \( _{56}^{137}\text{Ba}^{2+} \)

1. **Identify the Atomic Number and Mass Number**:
- The atomic number (Z) of Barium (Ba) is 56. This means it has 56 protons.
- The mass number (A) is 137.

2. **Determine the Number of Protons**:
- The number of protons is equal to the atomic number, so:
\[ \text{Number of Protons} = 56 \]

3. **Determine the Number of Electrons**:
- Since it is a \( \text{Ba}^{2+} \) ion, it has lost 2 electrons. Therefore:
\[ \text{Number of Electrons} = 56 - 2 = 54 \]

4. **Calculate the Number of Neutrons**:
- The number of neutrons can be calculated using the formula:
\[ N = A - Z \]
- So:
\[ \text{Number of Neutrons} = 137 - 56 = 81 \]

### Summary for (i):
- Electrons: 54
- Protons: 56
- Neutrons: 81

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### (ii) For \( _{9}^{19}\text{F}^{-} \)

1. **Identify the Atomic Number and Mass Number**:
- The atomic number (Z) of Fluorine (F) is 9. This means it has 9 protons.
- The mass number (A) is 19.

2. **Determine the Number of Protons**:
- The number of protons is equal to the atomic number, so:
\[ \text{Number of Protons} = 9 \]

3. **Determine the Number of Electrons**:
- Since it is a \( \text{F}^{-} \) ion, it has gained 1 electron. Therefore:
\[ \text{Number of Electrons} = 9 + 1 = 10 \]

4. **Calculate the Number of Neutrons**:
- The number of neutrons can be calculated using the formula:
\[ N = A - Z \]
- So:
\[ \text{Number of Neutrons} = 19 - 9 = 10 \]

### Summary for (ii):
- Electrons: 10
- Protons: 9
- Neutrons: 10

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### (iii) For \( _{88}^{226}\text{Ra} \)

1. **Identify the Atomic Number and Mass Number**:
- The atomic number (Z) of Radium (Ra) is 88. This means it has 88 protons.
- The mass number (A) is 226.

2. **Determine the Number of Protons**:
- The number of protons is equal to the atomic number, so:
\[ \text{Number of Protons} = 88 \]

3. **Determine the Number of Electrons**:
- Since it is a neutral atom (no charge), the number of electrons is equal to the number of protons:
\[ \text{Number of Electrons} = 88 \]

4. **Calculate the Number of Neutrons**:
- The number of neutrons can be calculated using the formula:
\[ N = A - Z \]
- So:
\[ \text{Number of Neutrons} = 226 - 88 = 138 \]

### Summary for (iii):
- Electrons: 88
- Protons: 88
- Neutrons: 138

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### Final Summary of All Parts:
1. **(i)** \( _{56}^{137}\text{Ba}^{2+} \): Electrons: 54, Protons: 56, Neutrons: 81
2. **(ii)** \( _{9}^{19}\text{F}^{-} \): Electrons: 10, Protons: 9, Neutrons: 10
3. **(iii)** \( _{88}^{226}\text{Ra} \): Electrons: 88, Protons: 88, Neutrons: 138

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