How do we know that air we breathe is matter?

Which of the following shapes would represent a molecule with two bonded atoms and 3 lone pairs on only one of them , trigonal planar , bent , trigonal pyramidal , linear

Anurse used a 0.02-mg/l solution of disinfection to clean a patients wound. what is the concentration of the solution expressed as a percentage?

Witch two conditions can limit the usefulness of the kinetic molecular theory in describing gas behavior?