What restricts the flow of electrons in a circuit?

How many moles are in 250 grams of tungsten (w)? * 4.4x10^23 moles 4.2x10^23 moles 0.7 moles 1.4 moles

If anyone would be able to me out with these three questions it would be these are from the chem 2202 course.

You open a can of soda at room temperature and hear a hiss. which of the following factors has changed inside the container? a.) atmospheric pressure b.) temperature of gas c.) type of gas d.) amount of gas