How many of the following metal chlorides impart characteristic colour to the lower oxidising flame?
LiCl, NaCl, KCl, `BeCl_(2), MgCl_(2), CaCl_(2), SrCl_(2), BaCl_(2)`

Explanation

To determine how many of the given metal chlorides impart characteristic color to the lower oxidizing flame, we need to analyze each of the metal chlorides listed:

1. **Identify the Metal Chlorides**:
- LiCl (Lithium Chloride)
- NaCl (Sodium Chloride)
- KCl (Potassium Chloride)
- BeCl₂ (Beryllium Chloride)
- MgCl₂ (Magnesium Chloride)
- CaCl₂ (Calcium Chloride)
- SrCl₂ (Strontium Chloride)
- BaCl₂ (Barium Chloride)

2. **Group Classification**:
- The metal chlorides can be classified into Group 1 (Alkali Metals: Li, Na, K) and Group 2 (Alkaline Earth Metals: Be, Mg, Ca, Sr, Ba).

3. **Flame Test for Alkali Metals**:
- Alkali metals (Li, Na, K) impart characteristic colors to the flame:
- LiCl gives a crimson red flame.
- NaCl gives a bright yellow flame.
- KCl gives a lilac flame.

4. **Flame Test for Alkaline Earth Metals**:
- Alkaline earth metals (Ca, Sr, Ba) also impart characteristic colors to the flame:
- CaCl₂ gives an orange-red flame.
- SrCl₂ gives a crimson flame.
- BaCl₂ gives a green flame.

5. **Exceptions**:
- BeCl₂ and MgCl₂ do not impart characteristic colors to the flame. This is due to:
- Their smaller atomic size leading to a higher effective nuclear charge, which makes it difficult for electrons to be excited to higher energy levels.
- Their high ionization energies, which also prevent the excitation of electrons.

6. **Counting the Metal Chlorides**:
- The metal chlorides that impart color to the flame are:
- LiCl
- NaCl
- KCl
- CaCl₂
- SrCl₂
- BaCl₂
- Total = 6 metal chlorides.

**Final Answer**: 6 metal chlorides impart characteristic color to the lower oxidizing flame.

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