Which statements describe processes involved in the accretion of planetesimals and protoplanets? Check all tha apply. Both involve the melting of solid materials in the nebula. Both involve the formation of solid particles from nebular materials. Both involve the work of the gravitational push on nebular materials. Both involve the trapping of gases and the clumping of masses of matter. Both involve the growing of gas grains with the addition of atoms and molecules.​