Energy that comes from ancient plants and animals includes

What does x represent in the formula for the compound xcl4?

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.

Which scientists contributed to the determination of how cfcs in clouds in the upper atmosphere could destroy ozone molecules