State true or false
CuSO4.5H2O is blue in colour while CuSO4 is colourless

Answer

To determine whether the statement "CuSO4.5H2O is blue in colour while CuSO4 is colourless" is true or false, we can analyze the properties of both compounds.

### Step 1: Identify the compounds
- **CuSO4.5H2O** is known as copper(II) sulfate pentahydrate.
- **CuSO4** is known as anhydrous copper(II) sulfate.

### Step 2: Examine the color of CuSO4.5H2O
- Copper(II) sulfate pentahydrate (CuSO4.5H2O) is known to be blue in color. This blue color is due to the presence of water molecules that act as ligands around the copper ions.

### Step 3: Examine the color of CuSO4
- Anhydrous copper(II) sulfate (CuSO4) is colorless. When it is dehydrated, it loses the water molecules and does not exhibit any color.

### Step 4: Explain the reason for the color difference
- The color in CuSO4.5H2O arises from crystal field splitting caused by the water molecules acting as ligands. This leads to d-d transitions in the copper ions, allowing them to absorb certain wavelengths of light and reflect blue light.
- In contrast, in anhydrous CuSO4, the absence of water means there is no ligand field to cause splitting, resulting in a colorless appearance.

### Conclusion
Based on the analysis, the statement "CuSO4.5H2O is blue in colour while CuSO4 is colourless" is **True**.

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