Stacy runs a paper chromatography experiment using the same ink, but two different solvents. using solvent a results in the ink separating into three bands, but solvent b does not carry the ink away from the original spot.
which of the following could explain the results?
a) solvent a was not a good mobile phase because it could not dissolve the ink.
b) solvent b was not a good mobile phase because it could not dissolve the ink.
c)the ink was a pure substance and dissolved in both solvents.
d) the ink was a mixture, but only in solvent a.

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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.