What mass of oxygen forms from 71.89 g CO2? Use the periodic table to find molar masses.

Iknow the answer is a but i don't know why

How manyatoms of mercury are in 1.4214e+1 ml sample

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.