A 8.85 g sample of hydrate of sodium carbonate, Na2CO3 ∙ XH2O was heated carefully until no more mass was lost from the sample. After heating, the final weight of the material was 7.55 g. How many moles of Na2CO3 remained after heating?

How air particles exert a pressure on the inside of the balloon

Asolution of sodium hydroxide was titrated against a solution of sulfuric acid. how many moles of sodium hydroxide would react with 1 mole of sulfuric acid?

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.