Give an example of a reaction where the following are involved.
Close contact

Explanation

To provide a step-by-step text solution for the question, we will break down the example reaction involving close contact between reactants.

### Step 1: Identify the Reactants
In this example, we will use lead(II) nitrate (Pb(NO3)2) and potassium iodide (KI) as the reactants.

### Step 2: Write the Chemical Equation
When lead(II) nitrate and potassium iodide are mixed, they undergo a double displacement reaction. The chemical equation for this reaction can be written as follows:

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