which compound has the highest melting point?\no $al_2(co_3)_3$\no $c_{12}h_{22}o_{11}$\no $c_8h_{18}$\no…

Explanation:

Step1: Identify compound types

$Al_2(CO_3)3$ is an ionic compound. $C{12}H_{22}O_{11}$ (sucrose) and $C_8H_{18}$ (octane) are covalent - molecular compounds, and $H_2O$ is a polar covalent - molecular compound.

Step2: Recall melting - point trends

Ionic compounds have stronger electrostatic forces between ions compared to the intermolecular forces (such as van der Waals forces and hydrogen - bonding) in molecular compounds.

Step3: Compare intermolecular forces in molecular compounds

Among molecular compounds, $C_{12}H_{22}O_{11}$ has more atoms and stronger van der Waals forces than $C_8H_{18}$, and $H_2O$ has hydrogen - bonding. But these intermolecular forces in molecular compounds are still weaker than the ionic bonds in $Al_2(CO_3)_3$.

Answer:

$Al_2(CO_3)_3$