What allows you to evaluate a single food and to compare the nutritional value of different foods?

What is the type of the reaction below? bacl2 + h2so4 → 2 hci + baso4 double replacement synthesis single replacement decomposition

Avery hard rubber ball (m = 0.5 kg) is falling vertically at 4 m/s just before it bounces on the floor. the ball rebounds back at essentially the same speed. if the collision with the floor lasts 0.05 s, what is the average force exerted by the floor on the ball?

Can anybody me with this? ? (picture included.)