Choose all the right answers. Why are lubricants necessary?

reduce friction
used as fuel
decrease loss of energy
increase heat energy

Amount of liquid measured in l or lm

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.

0.09 moles of sodium sulfate in 12 ml of solution