Okay i need with this. we are just beginning this cross multiply thing again and i forgot how to use it. he was very vague about it, here is the question.

The air that we breath is made mostly of which gaseous molecule

(a) calculate the number of electrons in a small, electrically neutral silver pin that has a mass of 10.0 g. silver has 47 electrons per atom, and its molar mass is 107.87 g/mol. (b) imagine adding electrons to the pin until the negative charge has the very large value 1.00 mc. how many electrons are added for every 109 electrons already present

Looking at this barometer, is the air pressure high or low? what type of weather would you expect? high, bad low, bad high, good low, good