The number of nucleons in the isotope of an atom `._(Z)X^(m)` are

Options

A. m
B. Z
C. `m+Z`
D. `m-Z`

Answer

To determine the number of nucleons in the isotope of an atom represented as `._(Z)X^(m)`, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Notation**: In the notation `._(Z)X^(m)`, `Z` represents the atomic number, and `m` represents the mass number of the isotope. The atomic number (`Z`) indicates the number of protons in the nucleus, while the mass number (`m`) represents the total number of nucleons (which includes both protons and neutrons).

2. **Define Nucleons**: Nucleons are the particles found in the nucleus of an atom, which include protons and neutrons. Therefore, the total number of nucleons in an atom can be calculated using the mass number.

3. **Identify the Mass Number**: The mass number `m` is defined as the sum of the number of protons and the number of neutrons. In mathematical terms, this can be expressed as:
\[ \text{Mass Number (m)} = \text{Number of Protons (Z)} + \text{Number of Neutrons (N)} \]
However, for the purpose of this question, we are specifically interested in the total number of nucleons, which is simply the mass number `m`.

4. **Conclusion**: Since the mass number `m` directly represents the total number of nucleons in the atom, we conclude that the number of nucleons in the isotope `._(Z)X^(m)` is equal to `m`.

### Final Answer:
The number of nucleons in the isotope of an atom `._(Z)X^(m)` is **m**.