Which of the following statements in incorrect ?

Options

A. a. Mg burns in air releasing dazzling light rigch in UV rays.
B. b. Alkaline earth metals are strong reducing agent.
C. c. Gypsum on heating at `393K` gives plaster of paris
D. d. Beryllium chloride tends to form a chloro`-` bridged dimer in the solid state and is soluble in organic solvents.

Explanation

To determine which statement is incorrect among the given options, we will analyze each statement one by one.

### Step-by-Step Solution:

1. **Statement 1: Magnesium burns in air releasing dazzling light rich in UV rays.**
- **Analysis:** When magnesium burns in the presence of oxygen, it produces magnesium oxide (MgO) and emits a bright light, which is indeed rich in ultraviolet (UV) rays. This statement is correct.

2. **Statement 2: Alkaline earth metals are strong reducing agents.**
- **Analysis:** Alkaline earth metals (like magnesium, calcium, etc.) are highly electropositive and readily lose electrons to form cations. This property makes them effective reducing agents, as they can reduce other substances by donating electrons. This statement is also correct.

3. **Statement 3: Gypsum on heating at 393 Kelvin gives plaster of Paris.**
- **Analysis:** Gypsum (CaSO4·2H2O) when heated to around 393 Kelvin (120°C) loses water and converts to plaster of Paris (CaSO4·0.5H2O). This statement is true.

4. **Statement 4: Beryllium chloride tends to form a chloro bridged dimer in the solid state and is soluble in organic solvent.**
- **Analysis:** In the vapor phase, beryllium chloride (BeCl2) exists as a chloro bridged dimer. However, in the solid state, it forms a linear polymeric structure rather than a dimer. Therefore, this statement is incorrect.

### Conclusion:
The incorrect statement is **Statement 4**: "Beryllium chloride tends to form a chloro bridged dimer in the solid state and is soluble in organic solvent."

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