Alkali metals give colour in Bunsen flame due to

Options

A. low ionisation potential
B. low m.p.
C. softness
D. one electron in the outermost orbit.

Explanation

To answer the question "Alkali metals give color in Bunsen flame due to," we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Flame Colors**: Alkali metals produce characteristic colors when heated in a Bunsen flame. This phenomenon occurs because of the excitation of electrons.

2. **Electron Excitation**: When alkali metals are heated, the energy from the flame causes electrons in the metal atoms to absorb energy and jump from their ground state to an excited state.

3. **Return to Ground State**: After a brief period, these excited electrons cannot remain in the excited state for long. They return to their ground state.

4. **Energy Release**: As the electrons return to the ground state, they release energy. If this energy falls within the visible spectrum of light, it is observed as color.

5. **Role of Ionization Potential**: Alkali metals have low ionization potentials, which means that it requires less energy to excite the electrons. This property is due to their large atomic size and the presence of a single electron in their outermost shell.

6. **Analyzing the Options**:
- **Option A**: Low ionization potential - This is correct because it allows electrons to be easily excited.
- **Option B**: Low melting point - This is not related to color production in flames.
- **Option C**: Softness - This is also not related to the flame color.
- **Option D**: One electron in the outermost shell - While this is true for alkali metals, it does not directly explain the color in the flame.

7. **Conclusion**: The correct answer is **Option A: due to low ionization potential**.