7. Spark plug is one of the components of a gasoline engine. What is the function of the spark plug? A. It pushes the piston down. B. It pushes the piston up. C. It ignites the fuel-air mixture. D. It pushes the gases out of the cylinder. 8. The change in the internal energy is dependent on heat and work. What happens to the internal energy when both heat transfer and work done by the system are equal? A. The internal energy increases. C. The internal energy remains the same. B. The internal energy decreases. D. The internal energy is zero. 9. In a gasoline engine, valves are present. Which valve opens as the fuel-air mixture fills in the cylinder? A. Intake valve B. Entry valve C. Exit valve D. Exhaust valve. 10. What is the net change in internal energy if the amount of work done by the system is the same amount as the amount of energy transferred in by heat? A. The net change in internal energy is 100. B. The net change in internal energy is 1. C. The net change in internal energy is 0. D. The net change in internal energy cannot be determined