Nucleus of an atom is negatively charged. why?​

What three things does a balanced equation show you?

The size (radius) of an oxygen molecule is about 2.0 ×10−10m. make a rough estimate of the pressure at which the finite volume of the molecules should cause noticeable deviations from ideal-gas behavior at ordinary temperatures (t= 300k ). assume that deviatons would be noticeable when volume of the gas per molecule equals the volume of the molecule itself.

Ahelium balloon contains 16.9 l of helium at stp. how many atoms of helium are in the balloon