What is polling used for?

Question 1:What is polling used for? What are the disadvantages of polling? What is a better way to perform the same job?Question 2:A 1600-pixel by 900-pixel display is generated on a 14-inch (diagonal) monitor.a. How many dots per inch are displayed on this monitor?b. What is the size of an individual pixel? Would a 0.26mm pixel resolution monitor be sufficient     for this display?c. Repeat (a) and (b) for a 1280 × 720 display.Question 3:When people describe client–server architecture, they are usually referring to a system in which a large server is serving a client on a PC. With X Window, the reverse is frequently the case. Explain.Question 4:What are the advantages of partitioning a disk, rather than using the entire disk as one partition?”Question 5: Describe CPU scheduling.