The process in which liquid water changes into gas is called

Describe the difference between a. a hypothesis and a theory and b. an observation and an experiment.

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.

Read "who built the pyramids? ”. leave this link open while you answer the questions throughout the assignment. give at least two reasons why some people claim the pyramids of giza were constructed by aliens.