Which of the following lists contain only elements?
a. air, iron, iodine, magnesium.
b. zinc, gold, aluminium, oxygen.
c. nitrogen, copper, mercury, water.
d. chlorine, argon, sodium, limestone.

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.

Which of the following would have less momentum than a 52 kg cheetah running at 10 m/s?

13. a covalent bond between two atoms is likely to be polar if: a. one of the atoms is much more electronegative than the other. b. the two atoms are equally electronegative. c. the two atoms are of the same element. d. the bond is part of a tetrahedrally shaped molecule. e. one atom is an anion.