Question 8At higher concentrations, alkali metal cations with an ionic radius close to that of a potassium ion can displace potassium ions in biological systems and promote low potassium levels (hypokalemia).  Which cation is most likely to displace K+ ions?A.Li+B.Rb+C.Cs+D.Fr+

The cation most likely to displace K+ ions in biological systems would be Rb+. This is because the ionic radius of Rb+ is closest to that of K+ among the given options.

Here's the step by step reasoning:

1. The question states that alkali metal cations with an ionic radius close to that of a potassium ion can displace potassium ions in biological systems.

2. Alkali metals in the periodic table are Lithium (Li), Sodium (Na), Potassium (K), Rubidium (Rb), Cesium (Cs), and Francium (Fr).

3. The ionic radius increases as you move down the group in the periodic table. This means that Li+ has the smallest ionic radius and Fr+ has the largest.

4. Given that we are looking for a cation with an ionic radius close to that of K+, we can rule out Li+ because its ionic radius is smaller than K+.

5. Similarly, we can rule out Cs+ and Fr+ because their ionic radii are larger than K+.

6. This leaves us with Rb+, which is right below K+ in the periodic table and has an ionic radius close to that of K+. Therefore, Rb+ is the most likely to displace K+ ions in biological systems.

So, the answer is B. Rb+.