If a rabbit consumes 500 calories of plant material how much that would be passed on to hawk in the food chain?

According to the 10% rule, only 10% of the energy consumed at one trophic level is passed on to the next trophic level. Therefore, if a rabbit consumes 500 calories of plant material, only 50 calories (10% of 500) would be passed on to a hawk that consumes the rabbit.