Acid precipitation is caused by a mix of
a. respiration, carbonic acids, and seawater.
b. water, soil, and air.
c. sulfur dioxide, carbon dioxide, and nitrogen oxides.
d. hydrogen, oxygen, and saline.

Which statement correctly describes other ways in which nebulae and stars are different? a. a star always has a higher density than a nebula. b. stars can form inside a nebula but a nebula can never be produced by any star. 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. reset submit