At a specific instant emission of radioactive compound is deflected in a magnetic field . The compound can emit
(i) electron (ii)protons(iii)`He^(2+ )`(iv) neutrons
The emission at instant can be

Options

A. `i, ii, iii`
B. `i, ii, iii, iv`
C. `iv`
D. `ii, iii`

Explanation

To solve the question about which emissions from a radioactive compound can be deflected in a magnetic field, we will analyze the options provided based on their charge properties.

### Step-by-Step Solution:

1. **Understanding the Problem**: We need to determine which of the emissions (electron, proton, helium nucleus, or neutron) can be deflected in a magnetic field.

2. **Identifying Charged Particles**:
- Electrons are negatively charged particles (charge = -e).
- Protons are positively charged particles (charge = +e).
- Helium nuclei (He²⁺) are positively charged particles (charge = +2e).
- Neutrons are neutral particles (charge = 0).

3. **Magnetic Force on Charged Particles**: The magnetic force acting on a charged particle moving in a magnetic field is given by the equation:
\[ F = Q(\mathbf{v} \times \mathbf{B}) \]
where \( Q \) is the charge of the particle, \( \mathbf{v} \) is the velocity, and \( \mathbf{B} \) is the magnetic field. Only charged particles will experience a magnetic force and thus can be deflected.

4. **Analyzing Each Option**:
- **Electrons**: Since they have a charge (-e), they will be deflected in a magnetic field.
- **Protons**: They have a charge (+e), so they will also be deflected.
- **Helium Nucleus (He²⁺)**: With a charge of +2e, it will be deflected as well.
- **Neutrons**: Being neutral (charge = 0), they will not experience any magnetic force and therefore will not be deflected.

5. **Conclusion**: The particles that can be deflected in a magnetic field are electrons, protons, and helium nuclei. Neutrons cannot be deflected.

### Final Answer:
The emission at the instant can be electrons, protons, or helium nuclei. Therefore, the correct options are (i) electrons, (ii) protons, and (iii) helium nuclei.