Question

What happens when a crystal structure of NaCl type is pressurized?

• A. The coordination number is decreased to 8 and converted to CsCl type crystal structure
• B. The coordination number is remains same
• C. The coordination number is increased to 8 and converted to CsCl type crystal structure
• D. The coordination number is increased to 4 and converted to ZnS type crystal structure

Answer 1

The correct option is A The coordination number is decreased to 8 and converted to CsCl type crystal structure

1) $NaCl$ crystal structure have 6:6 coordination number.

2) On applying pressure, ions come closer to each other which results in more compact structure (close-packed).

3) Thus increase in pressure changes the coordination number of $NaCl$ crystal from 6:6 to 8:8 which is $CsCl$ type crystal structure.

Therefore, the option is A.