Products and reactants in hydrogen gas and oxygen gas react to form water

What is common about these molecules? a. their atoms are held together by covalent bonds. b. they are all made up of the same two atoms. c. their atoms are held together by ionic bonds. d. they are all made up of oxygen atoms only.

Describe the interaction that occurs between two objects with the same electrical charge.

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.