The wind blows a lawn chair that weighs 4 kg into a fence with a force of 8 N. How much reaction force does the fence exert on the chair?

According to Newton's Third Law of Motion, for every action, there is an equal and opposite reaction. In this scenario, the lawn chair is being pushed against the fence with a force of 8 N due to the wind. Therefore, the fence will exert an equal reaction force of 8 N back on the chair.

So, the reaction force that the fence exerts on the chair is **8 N**.