Which is not true about the role of gravity in the formation of planets? Dust and gas particles that were attracted to each other began to rotate into a protoplanetary disk.
Gravity between planetesimals caused them to join together into conglomerate clumps. Our solar system is the only place in the universe where gravity played a key part in the formation of planets.
Gravity of larger objects in orbit around the sun attracted, and cleared the orbital path of, smaller planetesimals, gas, and dust.

Which statement is true if the refractive index of medium a is greater than that of medium b? a. total internal reflection is possible when light travels from air to medium b to medium a. b. total internal reflection is possible when light travels from medium a to medium b. c. total internal reflection is possible when light travels from medium b to medium a. d. total internal reflection is possible when light travels from air to medium a. e. total internal reflection is possible when light travels from air to medium b.