The Escape speed at the surface of a certain planet is twice that of the earth. If the planet has radius twice of the Earth. what is its mass in unit of earth's mass?​

Which statement is the best definition of an atom? a) anything that has mass and occupies space. b) the smallest particle that has the properties of an element. c) a substance that cannot be broken down chemically into simpler substances. eliminate d) the smallest unit of a substance that exhibits all of the properties characteristic of that substance.