If you gain internal validity do you lose external validity
All computers have an internal power supply... An external one is simply for back up if you lose power.
No it can not go through your skin but can get soaked up. It can yes. Your epidermis has keratin which reduces the lose or gain of fluid through your skin. Depending on you external environment fluid lose or gain may vary.
Lose
No. Atoms can gain and lose electrons but seldom gain or lose protons.
a closed system will not gain or lose mass
It doesn't lose or gain
They gain or lose electrons, while the atoms combine.
Neither lose nor gain.
Their internal osmolarity has to at least equal the osmolarity of the external environment or the cell will lose water to osmosis and die.
gain
gain 2
gain