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Nebulae are enormous clouds in outer space. they are made mostly of hydrogen gas, helium gas, and dust. some nebulae glow brightly, while others do not. the stars that people see are huge, bright balls of glowing gas. they are made mostly of hydrogen and helium. which statement correctly describes other ways in which nebulae and stars are different? a. stars can form inside a nebula but a nebula can never be produced by any star. b. a star always has a higher density than a nebula. c. stars can never form inside a nebula but a nebula can be produced by any star. d. a nebula always has a higher density than a star.

Movement that is like a t a type of wave that transfers energy where the particles in the medium move in a circle motion while the energy travels left or right. a type of wave that transfers energy where the particles in the medium move perpendicular to the direction in which the energy is traveling. transfers energy from one location to another a type of wave that transfers energy where the particles in the medium move parallel to the direction in which the energy is traveling. movement that is back and forth, like an equal sign = 1. wave 2. parallel movement 3. perpendicular movement 4. transverse wave 5. longitudinal wave 6. surface wave

Ascientist conducted an experiment and discovered that certain plants grow faster when given a particular amount of fertilizer. anouther scientist conducted the same experiment and got similar results. which concept does this best illustrate? a) repetition b) replication c) precision d) validity