Question

Which compound contains both ionic and covalent bonds?

• A. ${\mathrm{AlCl}}_3$
• B. $\mathrm{HCl}$
• C. ${\mathrm{NH}}_4\mathrm{Cl}$
• D. $\mathrm{KCl}$

Answer 1

The correct option is C

${\mathrm{NH}}_4\mathrm{Cl}$

Explanation for the correct options:

(c)

Ionic compounds: An ionic compound is a chemical compound composed of ions held together by electrostatic forces termed ionic bonding. The compound is neutral overall but consists of positively charged ions called cations and negatively charged ions called anions.

Covalent compounds: When a molecule is formed from the covalent bond, such compounds are known as covalent compounds. These compounds share one or more pairs of valence electrons. The covalent compound is a result of two non-metals reacting with each other such that they are electrically neutral.

Correct answer is ${\mathrm{NH}}_4\mathrm{Cl}$.

${\mathrm{NH}}_4\mathrm{Cl}$ (Ammonium Chloride) is an ionic compound as a bond is formed between ammonia (a polyatomic ion) and chlorine (a metal). The ammonium chloride molecule also consists of three covalent bonds, present between nitrogen and three hydrogen atoms, and a coordinate covalent bond between nitrogen and a hydrogen atom.

Explanation for the incorrect options:

(a) ${\mathrm{AlCl}}_3$ molecule is not an ionic compound because the difference in electronegativity value between aluminum and a chlorine atom is not big enough to make an ionic bond between them.

(b) $\mathrm{HCl}$ is a covalent compound because the electronegativity difference between hydrogen and chloride is less than 2.0. However, it is not a true covalent compound as chlorine is more electronegative than hydrogen and hence, it will attract a shared pair of electrons towards itself.

(d) $\mathrm{KCl}$ is an ionic compound because there is a large difference of electronegativity between the atoms.

Therefore, the correct option is (c) is ${\mathrm{NH}}_4\mathrm{Cl}$.