# Problem: Which isoelectronic series is correctly arranged in order of increasing radius?a. K+ &lt; Ca2+ &lt; Ar &lt; Cl -b. Cl - &lt; Ar &lt; K+ &lt; Ca2+c. Ca2+ &lt; Ar &lt; K+ &lt; Cl -d. Ca2+ &lt; K+ &lt; Ar &lt; Cl -e. Ca2+ &lt; K+ &lt; Cl - &lt; Ar

###### FREE Expert Solution

We’re being asked to determine the proper sequence of the given isoelectronic series based on increasing ionic radiusAn isoelectronic series means the given ions have the same number of electrons

Recall that ionic radius is the size of an ion

The trend for the ionic radius is as follows: it increases from right to left and down a period in the periodic table. Ionic radius also increases with an increasing number of electrons.

For this problem, we need to compare the charges of the ions in the isoelectronic series

This will help us arrange the ions in increasing ionic radius.

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###### Problem Details

Which isoelectronic series is correctly arranged in order of increasing radius?

a. K+ < Ca2+ < Ar < Cl -

b. Cl < Ar < K+ < Ca2+

c. Ca2+ < Ar < K+ < Cl -

d. Ca2+ < K+ < Ar < Cl -

e. Ca2+ < K+ < Cl - < Ar