Hydrogen fuel cells burn with and produce
a. water, oxygen
b. oxygen, water
c. carbon dioxide, oxygen
d. oxygen, carbon dioxide

As a part of an experiment a student burns propane to produce carbon dioxide and water she remembers that she must follow the law conservation of matter when writing a balanced chemical equation which of these equation adheres to the law of conservation of matter

Several kinds of bears are found on earth. most bears are brown or black, but one type of bear, the polar bear, is white. what process led to this difference in fur color? explain your answer.

Asample of aluminum foil contains 8.60 × 1023 atoms. what is the mass of the foil?