I need someone smart in science. Part 9.?

63.) Through which of the following will convection most likely occur? A.) liquids and gases B.) solids and liquids C.) solids D.) solids and gases





64.) Which if the following would be the best insulator? A.) air B.) aluminum C.) copper D.) silver





65.) When a ball rolls down a steep slope, what type of friction exists between the ball and the ground? A.) static friction B.) sliding friction C.) rolling friction D.) no friction, the ball is moving





68.) A cross-country runner runs 10km in 40 minutes. What is his average speed? A.) 4 km/min B.) 25 kn/min C.) 0.25 km/min D.) 0.4 km/min





69.) Find the acceleration of a car that goes from 32m/s to 96m/s in 8.0s. A.) 80m/s B.) -8.0m/s C.) -80m/s D.) 8.0m/s





70.) A 10-kg wagon has a speed of 25 m/s. What is its momentum? A.) 0.4kg x m/s B.) 2.5kg x m/s C.) 250kg x m/s D.) 25kg x m/s





71.) Calculate the force on an object that has a mass of 12kg and an acceleration of 4m/s. A.) 48N B.) 3N C.)8N D.)16N

I need someone smart in science. Part 9.?
63) A


64) A


65) C


68) C


69) D is close. Answer is 8.0 m/s^2.


I think that should qualify me for best answer.