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The size of Cl^(-) ion is 1.8Å . The siz...

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 `:`

A

`0.7452 Å`

B

`1.3176 Å`

C

`0.405 Å`

D

`1.8 Å`

Text Solution

Verified by Experts

Radius ratio
`0.414 lt= (r_(+))/(r_(-)) lt 0.732 " "6`
`0.732 lt= (r_(+))/(r_(-)) lt 1.00 " "8`
Hence use the radius ratio of 0.732 corresponding to the said change over from CN of 6 to CN of 8.
Hence cation size is `0.732xx1.8=1.3176Å.`
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