How many of following metals impart a characteristic colour to the Bunsen flame ?
`(i) Na " " (ii) Li " " (iii) K " " (iv) Ba`
`(v) Sr " " (vi) Mg " " (vii) Rb " " (viii) Cs`
(ix) `Be " " (x )Ca " " (x i)Cu`

Answer

To determine how many of the listed metals impart a characteristic color to the Bunsen flame, we will analyze each metal one by one based on their flame test results:

1. **Sodium (Na)**: Sodium imparts a **yellow** color to the flame.
2. **Lithium (Li)**: Lithium gives a **crimson red** color to the flame.
3. **Potassium (K)**: Potassium produces a **lilac** or **pinkish** color in the flame.
4. **Barium (Ba)**: Barium imparts a **pale green** or **apple green** color to the flame.
5. **Strontium (Sr)**: Strontium also produces a **crimson red** color in the flame.
6. **Magnesium (Mg)**: Magnesium does **not** impart any color to the flame.
7. **Rubidium (Rb)**: Rubidium gives a **red-violet** color to the flame.
8. **Cesium (Cs)**: Cesium produces a **blue** color in the flame.
9. **Beryllium (Be)**: Beryllium does **not** impart any color to the flame.
10. **Calcium (Ca)**: Calcium gives a **brick red** color to the flame.
11. **Copper (Cu)**: Copper imparts a **green** color to the flame.

Now, we will summarize the findings:

- Metals that impart a characteristic color:
- Sodium (yellow)
- Lithium (crimson red)
- Potassium (lilac)
- Barium (pale green)
- Strontium (crimson red)
- Rubidium (red-violet)
- Cesium (blue)
- Calcium (brick red)
- Copper (green)

- Metals that do not impart a characteristic color:
- Magnesium
- Beryllium

**Total Count of Metals that Impart Color**: 9 metals (Na, Li, K, Ba, Sr, Rb, Cs, Ca, Cu)

### Final Answer:
**9 metals impart a characteristic color to the Bunsen flame.**

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