Which of the following is true of both chlorine and sodium atoms?

When the following equation is balanced using the smallest possible integers, what is the coefficent of oxygen gas? c7h16o(g) + o2(g) → co2(g) + h2o(g) -1 -5 -8 -16 -21

Iwill give extra points to who gets this right

At 300 mm hg, a gas has a volume of 380 l, what is the volume at standard pressure