請教:ce Chem 一題mc

The answer is B. LiCl

For A, C and D, they have simple molecular structure. The molecules are attracted only by weak intermolecular forces. So little energy is required to overcome the attractive forces. So they have low melting points.

For B, it has a giant ionic structure. Cations and anions are attracted to each other by strong ionic bonds. A lot of energy is required to break these bonds and hence it has a high melting point.

Hint: Usually, a compound formed by by a metal cation and a non-metal anion has a giant ionic structure. Usually, ionic compounds have high melting points.

Usually, a compound formed by non-metals have low melting points.

B. LiCl

The answer is B.
HCl, SCl2 and CCl4 are all simple molecular structure.

Simple molecular structure are held by weak Van Der Waals' force(SCl2, CCl4) and Hydrogen bond(HCl).

However, LiCl is ionic structure, which is held by STRONG ionic bond.

The melting point depends on the strength of the bonds as stronger the bond, the higher the melting point.

Therefore B is the answer.