Question

Which of the following ions have highest ionic density?
A.${H^ + }$
B.$L{i^ + }$
C.$N{a^ + }$
D.${K^ + }$

Answer 1

We need to know that the ionic density is also known as ion concentration and it refers to the number of ions present in the unit volume of the given sample. The ions may be positive small ions, positive large ions, negative small ions and negative large ions etc. And the charge density is the ratio of the charge of the ion which is present in the volume. Hence, the ionic density depends on the number of ions present in the unit volume.

Complete answer:
Among the given ions, hydrogen ions have the highest ionic density. Because, the ionic density is the number of ions which is present in per unit volume. Here, the size of hydrogen ions is less than lithium, sodium and potassium ions. Therefore, hydrogen ions have a maximum number of ions present in a unit volume. Thus, it has high electron density. Hence, option (A) is correct.
The ionic density of lithium ions is less than hydrogen ions. Because, the size of $L{i^ + }$ is larger than hydrogen ions. Hence, the option (B) is incorrect.
The ionic density is inversely proportional to the size of the ion. And the size of sodium ions is larger than hydrogen ions. Thus, the ionic density of sodium ions is less than hydrogen ions. Hence, option (C) is incorrect.
The ionic density of potassium ions is less than hydrogen ions due to its size. Hence, the option (D) is incorrect.

Note:
We must have to remember that the ionic density mainly depends on the number of ions which are present in unit volume. Among the compounds hydrogen ions have the highest ionic density. The size is also a factor which affects the ionic density. The ionic density increases with decreasing the size of the ion. That time, the number of ions occupied at a unit volume will be increasing.