Answer- The particles in a solid gain enough energy to overcome the bonding forces holding them firmly in place. Typically, during melting, the particles start to move about, staying close to their neighbouring particles, then move more freely.
Answer:
I think its might be 1 because the ionic numbers for CA is +2 and for P its +3
Polar covalent bonds (because hydrogen and oxygen form polar bonds and are both nonmetals so it's covalent) and hydrogen bonds (because the water molecules are attracted to each other with partial charges, causing specific properties like surface tension).
So in my very bad drawing that I attached in case you're more a visual learner, the d- and d+ show the partial charges of hydrogen and oxygen (making it polar, as the electrons in the bond are more shifted towards oxygen, which is why oxygen has a negative sign) and the yellow dotted line show the hydrogen bonds.
Acceleration is the rate at which an object changes its speed. When a raindrop is falling down from the clouds due to gravity, the veloicty is pretty much fast, however air resistance comes in action and slows the droplet down... it gives it a constant speed until it hits the ground