Determine how many valence electrons magnesium contains

How many grams of oxygen gas are contained in a 15 l sample at 1.02 atm and 28°c? show your work.

Ammonium perchlorate nh4clo4 is the solid rocket fuel used by the u.s. space shuttle. it reacts with itself to produce nitrogen gas n2 , chlorine gas cl2 , oxygen gas o2 , water h2o , and a great deal of energy. what mass of nitrogen gas is produced by the reaction of 2.1g of ammonium perchlorate?

At stp, which substance is the best conductor of electricity? a. nitrogen b. neon c. sulfur d. silver