To solve the problem, we need to analyze the magnetic moments associated with electrons, protons, nuclei, and atoms. Let's go through each option step by step:
### Step 1: Understanding Magnetic Moment
Magnetic moment arises due to the motion of electric charges. In atoms, electrons revolve around the nucleus, creating a current loop which generates a magnetic moment.
### Step 2: Analyzing Electrons
- **Electrons**: Each electron has a magnetic moment due to its orbital motion around the nucleus. The motion of the negatively charged electron creates a current, which results in a magnetic moment. Therefore, the statement "all electrons have magnetic moment" is **true**.
### Step 3: Analyzing Protons
- **Protons**: Protons, being positively charged, also exhibit magnetic moments. Although they are located in the nucleus, the magnetic field generated by the revolving electrons can exert a torque on the protons, leading to a magnetic moment. Hence, the statement "all protons have magnetic moment" is also **true**.
### Step 4: Analyzing Nuclei
- **Nuclei**: Nuclei consist of protons and neutrons. While protons have a magnetic moment, the overall magnetic moment of a nucleus is very small due to the presence of neutrons, which do not contribute to the magnetic moment. Therefore, while nuclei can have magnetic moments, their magnitude is negligible in comparison to that of electrons. Thus, the statement "all nuclei have magnetic moment" can be considered **false** in practical terms.
### Step 5: Analyzing Atoms
- **Atoms**: An atom is electrically neutral overall, meaning that the positive charge of protons is balanced by the negative charge of electrons. The net current due to the motion of electrons can cancel out, leading to no net magnetic moment for the atom. Therefore, the statement "all atoms have magnetic moment" is **false**.
### Conclusion
Based on the analysis:
- The correct options are:
- A: All electrons have magnetic moment (True)
- B: All protons have magnetic moment (True)
- C: All nuclei have magnetic moment (False)
- D: All atoms have magnetic moment (False)
Thus, the correct answer is options A and B.
