26. What is the difference between Queue and Stack?

1. 1. Queue is LIFO; Stack is FIFO

   
   
   

   2. Stack and Queue is LIFO

   
   
   

   3. Stack is LIFO; Queue is FIFO

   
   
   

   4. Stack and Queue is FIFO

   
   
   

   5. None of these

   
   
   

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1. View Hint View Answer Discuss in Forum

   NA

   Correct Option: C

   Stack is Last in First out (LIFO) and Queue is First in First out(FIFO).

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27. What are the use of front and rear pointers in CircularQueue implementation?

1. 1. Rear pointer points to first element; front pointer points to the last element

   
   
   

   2. Front pointer points to the first element; rear pointer points to null object

   
   
   

   3. Front pointer points to first element; rear pointer points to the last element

   
   
   

   4. Front and read pointers point to the first element

   
   
   

   5. None of these

   
   
   

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1. View Hint View Answer Discuss in Forum

   NA

   Correct Option: D

   CircularQueue implementation is an abstract class where first and rear pointer point to the same object.

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28. What is the correct method used to insert and delete items from the queue?

1. 1. add and remove

   
   
   

   2. enqueue and peek

   
   
   

   3. push and pop

   
   
   

   4. enqueue and dequeue

   
   
   

   5. None of these

   
   
   

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1. View Hint View Answer Discuss in Forum

   NA

   Correct Option: D

   enqueue is pushing item into queue; dequeue is removing item from queue; peek returns object without removing it from queue.
   Stack uses push and pop methods. add and remove are used in the list.

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29. Which data structure is used in Breadth First Traversal of a graph?

1. 1. Array

   
   
   

   2. Stack

   
   
   

   3. Tree

   
   
   

   4. Queue

   
   
   

   5. None of these

   
   
   

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1. View Hint View Answer Discuss in Forum

   NA

   Correct Option: B

   In Breadth First Traversal of graph the nodes at the same level are accessed in the order of retrieval (i.e FIFO).

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30. Where does a new element be inserted in linked list implementation of a queue?

1. 1. All the old entries are pushed and then the new element is inserted

   
   
   

   2. At the centre of list

   
   
   

   3. Tail of list

   
   
   

   4. Head of list

   
   
   

   5. None of these

   
   
   

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1. View Hint View Answer Discuss in Forum

   NA

   Correct Option: C

   To maintain FIFO, newer elements are inserted to the tail of the list.

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