In tlc lab when you separated spinach pigments’, in previous years most sections found 45: 55 acetone: hexanes mobile phase composition to give the best results. in column chromatography, the best mobile phase turned out to be 40: 60 or 35: 65 acetone: hexanes. what is the reason that the exact mobile phase composition from tlc does not give the best separation in column chromatography? explain (4 pts)

Used the balanced equation 2h2+ o2 - -> 2h2o. if you have 7.2 grams of o2 , how many grams of h2o can you produce ?

This image is an example of a(n) a) atom. b) compound. c) mixture. d) molecule.

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.