Which of the following could lead to static discharge?
water molecules sticking together at a surface
the force of gravity pulling an object to Earth
a vibration compressing molecules of air
the build up of electrons on the atoms of an object

Static charge is caused by the build up of electrons on the atoms of an object.

Explanation:

You can experience this yourself with a balloon! Rub it against your head in order to disassociate electrons from it, causing it to be charged - you can now put it on a wall and notice how it 'sticks' to it. You can also cause this effect by jumping on a trampoline, causing static charge to be built up - which is sometimes why you feel a little 'zap' when you touch the sides of it.

the volume of fluid displaced would equal the volume of the gas. use a gas syringe - this is a laboratory instrument that can be used to withdraw a certain volume of gas from a closed system or to measure the volume of gas from a chemical reaction.

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.