Question

6 : 6 coordination number of $NaCl$ changes to 8 : 8 coordination on:

• A. increase in temperature
• B. both (A) and (B)
• C. no effect on coordination
• D. applying high pressure

Answer 1

The correct option is D applying high pressure

Temperature and pressure plays an important role in crystal structure of the compound.
On increasing the temperature, the coordination number of constituents in compound tends to decrease.
On increasing the pressure, the coordination number tends to increase.
The coordination number of 6:6 of $NaCl$ type can be coverted to coordination number of 8:8 of $CsCl$ type by apply high pressure.
Similary, coordination number of 8:8 of $CsCl$ type can be coverted to coordination number of 6:6 of $NaCl$ type by increasing the temperature.