Fill in the blanks:
$(i)$ As the surface area is large,the potential energy of the molecules is ...... (more / less).
$(ii)$ As the surface area is small,the potential energy of its molecules is ...... (more / less).

(A) The potential energy of molecules at the surface of a liquid is greater than that of molecules in the interior because surface molecules experience a net inward force.
$(i)$ When the surface area is large,more molecules are present at the surface,which means the total potential energy of the surface molecules is more.
$(ii)$ When the surface area is small,fewer molecules are present at the surface,which means the total potential energy of the surface molecules is less.
Therefore,the answers are $(i)$ more and $(ii)$ less.