What is Demodulation ?

What is phase difference ? What is relation between phase and path difference ?

Fill in the blank spaces with appropriate answers. Demodulation is the method of recovering of __________ signal from the modulated carrier in radio communication (audio/radio)

What is 'Evaporation ,what factors affect it, explain.

What are natural rubbers and what are synthetic rubbers? What is vulcanisation? How does it improve the characteristics of rubbers?