A student is trying to identify an unknown substance. He finds the mass of a weigh boat, 2.69 g, and the mass of the substance in the weigh boat, 18.01 g. To find the volume he measured out 25.7 mL of water in a graduated cylinder and then added the substance and recorded a new measurement, 32.3 mL.

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When the water vapor cools it condenses select a number that represents his process on the

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.