I think the correct answer from the choices listed above is the second option. The difference between speed and velocity would be that speed <span> requires distance. Velocity requires displacement. Speed only has a magnitude while velocity is a vector quantity which means it has direction and magnitude.</span>
#1
<span>The rate of diffusion of a gas is inversely proportional to the square root of its molecular weight.
#2
shape, molecular weight. I don't know for sure though
#3
</span>O2, N2, Ar, H2O vapor
Your answer to this question would be True.
Hope I helped:P
Molecular is existent due to being made out of molecules, and thus taking up space until a container cannot hold more.
Ionic substances are a little different they are made out of energy, thus taking up only the amount of energy a certain area can handle. Ionic substances also will show motion of energy as well.