The size of `Cl^(-)` ion is `1.8Å` . The size of a cation for which a change in coordination just becomes possible from 6 to 8 in an ideal ionic crystal would be `:`

Options

A. `0.7452Å`
B. `1.3176Å`
C. `0.405Å`
D. `1.8Å`

Answer

2

Explanation

`{:(R R R,,CN),(0.414 le (r_(+))/(r_(-)) lt 0.732,,6),(0.732 le (r_(+))/(r_(-)) lt 1.00,,8):}`
Hence use the RR of `0.732` corresponding to the said changeover from CN of 6 to CN of 8.
Hence cation size is `0.732xx1.8=1.3176Å`