$A$ sponge is a solid,yet we are able to compress it. Why?

At what temperature does solid ice and liquid water co-exist together (in $0^{\circ} C$)?

What happens when you open a bottle of perfume?

$(a)$ Enumerate the changes that take place inside the matter during the change of states.
$(b)$ When a solid melts,its temperature remains the same. Give reason.

Give reasons for the following:
$(i)$ $A$ gas exerts pressure on the walls of the container.
$(ii)$ $A$ gas fills the vessel in which it is kept.

$(i)$ Name the $SI$ unit of measuring temperature.
$(ii)$ The boiling point of water is $100^{\circ} C$ under normal atmospheric pressure. Convert this temperature into $SI$ units.