What is the approximate weight of a 20-kg cannonball on the moon if the acceleration due to gravity is 1.6 m/s2?
2 n 20 n 32 n 196 n

Weight, which is a force, is mass times acceleration:
20 kg*1.6 m/s²=32 N

Answer sample (c); // would be best because the percentage of the energy in an incident wave that remains in a reflected wave from this material is the smallest;

Answer4 million;