Why don't we notice the quantization of energy in everyday life?

We do not notice the quantization of energy in everyday activities becausequantization means that particles are made up of a finite amount of units of energy. Also, quantization of energy is only seen in the atoms and atoms can only take up certain discrete values of energy.

How is X-Ray produced in a lab?

Well, an interesting question indeed.

The basic principle for the production of X-ray is by deccelerating very fast moving electrons, so here might arise a question what happens to the energy of electrons? The energy of electrons is transferred to X-rays(minimum) and Heat energy. 

How do we deccelerate the fast moving electrons?

Simply by resistance force, for a fast moving electron, the energy possessed by it must be high, so we deccelerate the electrons by a target material which is of...

What is meant by quantization of angular momentum?

In an orbit, the angular momentum is always quantized. Quantization means that a quantity can vary only discontinuously to get a specific value i.e. the orbits are possible only after a certain separation and they are not possible continuously.