Question

Which of the following is an ionic compound?

• A. $S{O}_3$
• B. $ICl$
• C. $KI$
• D. $CHC{l}_3$

Answer 1

The correct option is C $KI$

Ionic bond is formed between an metal and a non-mrtal.
To form an ionic bond, the bonded elements should have a large difference in electronegativity or in other words the ionisation energy of one should be low and the electron affinity of the other atom should be high.

$S{O}_3:$ Sulphur and Oxygen are both non-metals. Therefore, $S{O}_3$ is a covalent compound.

$ICl:$ Iodine and Chlorine are both halogen. Thus both have the tendency to gain electrons. Therefore, $ICl$ is a covalent compound.

$KI:$ Potassium is a metal and Iodine is a non-metal. Therefore, $KI$ is an ionic compound due to the greater electronegativity difference between the two elements.

$CHC{l}_3:$ Carbon, hydrogen and chlorine are all non-metals and therefore $CHC{l}_3$ is a covalent compound.