Explain : "diamond is hard , whereas graphite is soft"

Explain ETS.

Explain Mutation.

Explain ionic solids are hard and brittle.

Explain the formation of scum when hard water is treated with soap.

Explain how a square is. a rectangle

Give reasons for the following: On the basis of heat of combustion values, graphite is more stable than diamond. However, diamond does not change into graphite for years together.

The refractive index of diamond is 2.42. What is the meaning of this statement?

Light enters from air to diamond which has refractive index of 2.42. Calculate the speed of light in diamond . The speed of light in air is 3.0 xx 10^8 m s^-1