1. CMOS Complementary metal–oxide-semiconductor
CMOS is the combination of NMOS and PMOS in a single device. Means in CMOS both NMOS and PMOS are there in single device.
CMOS technology is used in microprocessors, microcontrollers, static RAM, and other digital logic circuits.
Two important characteristics of CMOS devices are high noise immunity and low  power consumption.

2. The phrase "metal–oxide–semiconductor" is a reference to the physical structure of certain field-effect transistors, having a metal gate electrode placed on top of an oxide insulator, which in turn is on top of a semiconductor material.

4. Explanation for oscillation to occur

6. Two important criteria for oscillation to occur:-
Loop Gain
Aβ=1
And phase change:-
Θ=3600

7. Oscillators classificationn:-

8. RC phase shift oscillator

13. LC Oscillators