Here's how to write the equation for the single displacement reaction between bromine and calcium iodide:

1. Identify the reactants and products:

* Reactants: Bromine (Br₂) and Calcium Iodide (CaI₂)

* Products: Calcium Bromide (CaBr₂) and Iodine (I₂)

2. Write the unbalanced equation:

Br₂ + CaI₂ → CaBr₂ + I₂

3. Balance the equation:

The equation is already balanced.

4. The final balanced chemical equation:

Br₂ + CaI₂ → CaBr₂ + I₂

Explanation:

* Bromine (Br₂) is more reactive than iodine (I₂), so it displaces iodine from calcium iodide.

* This results in the formation of calcium bromide (CaBr₂) and elemental iodine (I₂).

Important Note: This reaction is an example of a single displacement reaction, where a more reactive element replaces a less reactive element in a compound.