Ascientist observes that an unknown solution turns blue litmus paper red and reacts with zinc to produce hydrogen gas. which of the following best describes the unknown solution.

a. a colloid
b. an acid
c. a base
d. a suspension

All of the following are part of the biosphere except

Which process does not require the presence of a physical substance in order to transfer heat? air in the atmosphere is heated by the ground. this warm air then rises, and cooler air falls. this is an example of what type of process? how is conduction different from radiation?

What causes different colors to appear in the sky? the absorption of light by air molecules the reflection of light by bodies of water the greenhouse effect in earth's atmosphere the scattering and reflection of light by dust particles