Why do covalent compounds tend to have lower melting points than ionic compounds?

Because ionic compounds' strong bonds form network structures, which have a stronger attraction than the covalent compounds which are molecules.

Simple molecular substances consist of molecules in which the atoms are joined by strong covalent bonds. Their molecules are held together by weak forces, so these substances have low melting and boiling points. ... They have high melting and boiling points.

The answer is 1.82 j/g°c