If L is recursively enumerable that means a TM accepts all strings in L. ~L is recursively enumerable means that a TM accepts all strings in ~L.So we can always decide if a string is in L or not. Since we can always decide so it is recursive.

If transition is not defined in any state,then the state may be final or non final state.In both case it is said that the machine halts.If in final state there is no transition then we say machine halts and we say string accepted or if in non-final state there is no transition then we say machine halts and we say string is rejected.

A language L may not be accepted by a Turing machine if L is not recursively enumerable. But note that if L is recursively enumerable then it will be definitely accepted by TM.

The variable which produces an epsilon is called nullable variable.

The construction time for a DFA from an NFA is O(2^m) where m is the number of nodes in NFA because if no. of nodes in NFA is m then DFA can have upto 2^m states.

File is logical storage unit with set of physical blocks

The address generated by the CPU is a logical address, whereas the address actually seen by the memory hardware is a physical address

Inter process communication is a set of programming interface which allow a programmer to coordinate activities among various program processes which can run concurrently in an operating system.

Among the given devices magnetic disk has the highest access time.

A PID (i.e., process identification number) is an identification number that is automatically assigned to each process when it is created on a Unix-like operating system. A process is an executing (i.e., running) instance of a program. Each process is guaranteed a unique PID, which is always a non-negative integer.

points. Circuit switching method is also called a connection oriented network. Two nodes must be physically and logically connected to each other to create a circuit switching network.

Subnetting divides a network into smaller sections. It can have a number of purposes including easier network management and more organized networks, as well as various security and performance gains

In class C network first 24 bit is network id and next 8 bit is host id.
So in network mask of class C first 24 bit will have binary 1’s and next 8 bits will have binary 0’s.
So therefore network mask of class C will be 255.255.255.0

The space complexity of an AVL tree is O(n) in both the average and the worst case because the AVL tree is balanced BST and will require space almost equal to the space required by complete binary tree which is O(n). But the average space complexity can never be O(logn) since no. of elements are n.
Also time complexity for inserting an element in AVL tree is O(logn) since the tree is balanced binary search tree whose height is O(logn).

Strictly speaking an insertion is simply O(1). The other answers mostly correctly state that the complexity is O(n) if you need to search for the position in which to insert the new node