Consider the following statements: In centrifugal compressors, there is a tendency of increasing surge when i. the number of diffuser vanes is less than the number of impeller vanes ii. the number of...

Consider the following statements: In centrifugal compressors, there is a tendency of increasing surge when i. the number of diffuser vanes is less than the number of impeller vanes ii. the number of diffuser vanes is greater than the number of impeller vanes iii. the number of diffuser vanes is equal to the number of impeller vanes iv. mass flow is greatly in excess of that corresponding to the design mass flow Which of these statements is/are correct?