Ans 3
Zombie process: By default, the UNIX system assumes that if child process terminates , the parent process collects some data about the child. As soon as this collection is made, the system releases information bits about the child process and removes its pid from the process table. However, if the parent process fails to collect the child's data, the UNIX is forced to keep the child's pid and termination data in the process table indefinitely. Such a terminated process whose status is not collected is called a zombie process, or simply a zombie
Orphan process : opposite situation to zombie processes. In this a parent process terminates before its child processes. UNIX redefines the "parent PID" field in the child process's data to process init.
