The Solid State

Question 29

A cubic solid is made of two elements Y and Z. Atoms of Z are at the corners of the cube and Y at the body centre. What is the formula of the compound?


Number of Z per unit cell = 1/8 x 8Z = 1 Z.
Number of X per unit cell = 1 Y.
Formula of the compound = ZY.

Question 30

MgO has rock salt type structure. What is the co-ordination number of each ion?

The co-ordination number of each ion in MgO is six.
Question 31

Thallium chloride exists in Cs CI type lattice. What are the co-ordination number of TI and Cl ions?

The co-ordination number of each ion is 8. Thallium chloride is a 8:8 co-ordination lattice.
Question 32

What is the effect of pressure on NaCl type crystals?

High pressure increases the co-ordination number from 6:6 to 8:8.

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