Part A
If the partial pressures are oxygen 445 torr and helium 90 torr , what is the partial pressure (torr) of
the nitrogen in the mixture?

the density(ratio between mass and volume as m/v) decreases from top to bottom in periodic table group as the size increases and nuclear charge decreases. but in periods density increases from left to right as atom size decreases and nuclear charge increases.

it's c (engineer's do their work with mechanical stuff not on any living being)