Because if you have a liquid then you need a glass to keep it together and when it is a solid it is already together so you don't need to do anything
The formal charge of H = +1, because F in compounds can have only -1.
Al is the reducing agent.That is answer B is the above answer
Al acts as a strong reducing agent. It reduces crO3 to form cr while Al is oxidized to Al2O3. Al is capable to reduce cr since Al is higher in reactivity series than cr.
They have a mass for the particles
There are no totally elastic collisions
There are intermolecular forces
