Question

Identify the wrong statement among the following for two ionic solids,$KI$ and $CaO$$?$
A. Lattice energy of $CaO$ is much higher than that of $KI$.
B. $KI$ is soluble in benzene.
C. $CaO$ has a high melting point.
D. $KI$ has a high melting point.

Answer 1

Hint:Ionic solids are solids held together by ionic bonds. They are lattices composed of oppositely charged ions. Ionic solids tend to have high melting points ("high" generally being higher than metallic but lower than covalent).

Complete step by step answer:
We know that there are two types of solid, covalent and ionic. Let’s list down their characteristics.
Covalent solid: 1.They have low melting point and boiling point.
2. They are soluble in covalent liquids.
3. Lattice energy of covalent compounds is higher than that of ionic compounds.
4. Covalent solids are non-polar in nature, hence they are soluble in non- polar solvents.
5. Due to presence of free electrons in covalent solids, they are good conductor of
electricity.

Ionic solids: 1.They have high melting point and boiling point.
2. Ionic solids are polar in nature, that’s why they are soluble in polar solvents.
3. Lattice energy of ionic solids is lower than covalent compounds.
4. Due to absence of any free electrons, they are insulators. But in molten state, they dissolve in ions hence possess conductivity.
Let’s look at all the options one by one:-
A.Lattice energy of $CaO$ is much higher than that of $KI$.
True.
Explanation: $CaO$ is covalent in nature, so it possesses higher lattice energy than ionic compound.$KI$is ionic in nature so its lattice energy is low than the covalent solids.

B.$KI$ is soluble in benzene.
False.
Explanation:$KI$ is ionic in nature, and benzene is non- polar , so it is not soluble in it.

C.$CaO$ has a high melting point.
True.
Explanation: Melting point depends upon the size of the atom. Size of $Ca$ is bigger than $K$.

D.$KI$ has a high melting point.
True.
Explanation: Ionic compounds have a high melting point.

Note:Covalent or molecular compounds form when elements share electrons in a covalent bond to form molecules. Molecular compounds are electrically neutral. Ionic compounds are (usually) formed when a metal reacts with a nonmetal (or a polyatomic ion). Covalent compounds are formed when two nonmetals react with each other.