In TLC lab when you separated spinach pigments', 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

What layer of the atmosphere is directly above the troposphere?

1. explain hydrogen peroxide, h 2 o 2 properties and decomposition reaction. 2. describe how each of the following natural cycles plays a part in earth’s climate system. (a) the water cycle (b) the carbon cycle

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.