Which page replacement policy sometimes leads to more page faults when size of memory is increased?

At a particular time of computation the value of a counting semaphore is 7. Then 20 P operations and 15 V operations were completed on this semaphore. The resulting value of the semaphore is:

Which of the following is an example of a spooled device?

Which of the following statements is / are true / false?

Union of two recursive languages is recursive