Which one of the following statements is true?

Compared to reciprocating compressor, the performance of centrifugal compressor is less sensitive to speed

Surging in centrifugal compressor takes place as evaporator pressure increases and condenser pressure decreases

Surging in centrifugal compressor takes place as evaporator pressure decreases and condenser pressure increases

For a given flow rate, frictional losses decrease as the number of blades increases