Air is 23% oxygen by mass. What mass of air would be required in order to obtain 500 kilograms of oxygen?

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.

Scientists have developed an explanation of a phenomenon from several verified hypotheses. the explanation has been confirmed through numerous experimental tests.which option best describes this explanation? a. scientific lawb. research questionc. hypothesisd. scientific theory

Which symbol can be used to indicate the pressure at which a chemical reaction is carried out? 25°c 2 atm pa