Chemistry SQSA2 (20 Which one of the following molecular formulas is also an empirical formula?

H₂O₂
HP400
CoH8O2
C2H8SO

What is the molality of a solution that has 4 mol of kci in 0.800 kg of water

The answer for #3 is c but i don't know why

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.