Wohler prepared urea by heating a mixture of..........and............or simply by heating............ .

Answer

To answer the question regarding Wohler's preparation of urea, we can break down the process step by step:

### Step-by-Step Solution:

1. **Identify the Reactants**: Wohler prepared urea by heating a mixture of lead(II) cyanate (Pb(NCO)2) and ammonia (NH3).

2. **Reaction Process**: When lead(II) cyanate is heated with ammonia, it forms ammonium cyanate (NH4NCO).

3. **Decomposition of Ammonium Cyanate**: Ammonium cyanate then decomposes into urea (NH2CONH2) and ammonia (NH3).

4. **Final Product**: The final product of this reaction is urea, which can be represented by the formula NH2CONH2.

### Complete Answer:
Wohler prepared urea by heating a mixture of lead(II) cyanate and ammonia, or simply by heating ammonium cyanate.