Solve this, dont even kniw the abc of it

Choose all the answers that apply. our solar system: is in a spiral galaxy no longer includes pluto is made mostly of empty space is in the andromeda galaxy is the only known system that supports life

Two balls, each with a mass of 0.5 kg, collide on a pool table. is the law of conservation of momentum satisfied in the collision? explain why or why not

What is the efficiency of an engine that does 80 j of work and exhausts 320 j of heat while taking in 400 j of heat ? a. 10% b. 20% c. 80% d. 25%