In the nucleus of `""_(20)^(40)`Ca, there are

Options

A. 40 protons and 20 electrons
B. 20 protons and 40 electrons
C. 20 protons and 20 neutrons
D. 20 protons and 40 neutrons.

Explanation

To determine the number of protons, electrons, and neutrons in the nucleus of calcium represented as `""_(20)^(40)`Ca, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Atomic Number and Mass Number:**
- The notation `""_(20)^(40)`Ca indicates that the atomic number (Z) is 20 and the mass number (A) is 40.
- Here, Z = 20 (which represents the number of protons) and A = 40 (which is the total number of protons and neutrons).

2. **Determine the Number of Protons:**
- The number of protons in an atom is equal to its atomic number.
- Therefore, the number of protons in calcium is 20.

3. **Determine the Number of Electrons:**
- In a neutral atom, the number of electrons is equal to the number of protons.
- Hence, the number of electrons in calcium is also 20.

4. **Calculate the Number of Neutrons:**
- The number of neutrons can be calculated using the formula:
\[ \text{Number of Neutrons} = \text{Mass Number} - \text{Atomic Number} \]
- Substituting the values:
\[ \text{Number of Neutrons} = 40 - 20 = 20 \]

5. **Summarize the Results:**
- In the nucleus of `""_(20)^(40)`Ca, there are:
- 20 protons
- 20 electrons
- 20 neutrons

### Final Answer:
In the nucleus of `""_(20)^(40)`Ca, there are 20 protons and 20 neutrons.

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