Which of the following produce red coloured flame during flame test ?

Options

A. `Li`
B. `Ca^(2-)`
C. `Sr^(2-)`
D. `Ba^(2-)`

Answer

To determine which of the given options produces a red-colored flame during a flame test, we will analyze each of the elements mentioned: Lithium, Calcium, Strontium, and Barium.

### Step-by-Step Solution:

1. **Understanding Flame Test**:
- The flame test is a qualitative analysis technique used to identify the presence of certain metal ions based on the color of the flame produced when the metal is heated. Different metals emit different colors due to the excitation of electrons.

2. **Identifying the Elements**:
- The elements in question are:
- Lithium (Li)
- Calcium (Ca)
- Strontium (Sr)
- Barium (Ba)

3. **Analyzing Each Element**:
- **Lithium (Li⁺)**: When lithium ions are heated, they produce a red flame. This is a characteristic color for lithium.
- **Calcium (Ca²⁺)**: Calcium ions produce a brick red or orangish-red flame. While it is a shade of red, it is not the pure red that lithium produces.
- **Strontium (Sr²⁺)**: Strontium ions produce a crimson red flame. This is also a shade of red, but it is deeper than that of lithium.
- **Barium (Ba²⁺)**: Barium ions produce an apple green flame, which is distinctly different from red.

4. **Conclusion**:
- From the analysis, both Lithium and Strontium produce red flames, but the pure red flame is specifically characteristic of Lithium. Therefore, the answer to the question is that Lithium produces a red-colored flame during the flame test.

### Final Answer:
**Lithium (Li⁺)** produces a red-colored flame during the flame test.

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