Question

Which of the following has maximum value of cation/anion ratio?

• A. KCl
• B. NaCl
• C. $\ce{CaF_2}$
• D. $\ce{MgCl_2}$

Answer 1

Answer: (C)

$\ce{CaF_2}$

Answer 2

Among the three options ${KCl, NaCl}$ and ${MgCl_2}$ , the size of anion is same. So larger the cation, larger will be the cation/anion ratio i.e., KCl will have larger cation/anion ratio among the three. So, we left with two options KCl and ${CaF_2}$ . Among these two ${CaF_2}$ will have maximum value of cation/anion ratio because decrease in ionic radii of anion from ${Cl^{-}}$ to ${F^{-}}$ does not overcome the effect of decrease in ionic radii of cation from K+ to ${Ca^{2+}}$.