# MCQs on stacks with answers

## MCQs on stacks with answers

1. The postfix form of the expression (A+ B)*(C*D- E)*F / G is?

a) AB+ CD*E - FG /**
b) AB + CD* E - F **G /
c) AB + CD* E - *F *G /
d) AB + CDE * - * F *G /

ANSWER: a) AB+ CD*E - FG /**

2. The data structure required to check whether an expression contains balanced parenthesis is?

a) Stack
b) Queue
c) Array
d) Tree

3. What data structure would you mostly likely see in a non recursive implementation of a recursive algorithm?

b) Stack
c) Queue
d) Tree

4. The process of accessing data stored in a serial access memory is similar to manipulating data on a ------?

a) Heap
b) Binary Tree
c) Array
d) Stack

5. The postfix form of A*B+C/D is?

a) *AB/CD+
b) AB*CD/+
c) A*BC+/D
d) ABCD+/*

6. Which data structure is needed to convert infix notation to postfix notation?

a) Branch
b) Tree
c) Queue
d) Stack

7. The prefix form of A-B/ (C * D ⋀ E) is?

a) -/*⋀ACBDE
b) -ABCD*⋀DE
c) -A/B*C⋀DE
d) -A/BC*⋀DE

8. What is the result of the following operation
Top (Push (S, X))

a) X
b) Null
c) S
d) None

9. The prefix form of an infix expression p + q - r * t is?

a) + pq - *rt
b) - +pqr * t
c) - +pq * rt
d) - + * pqrt

ANSWER: c) - +pq * rt

10. Which data structure is used for implementing recursion?

a) Queue
b) Stack
c) Array
d) List

11. The result of evaluating the postfix expression 5, 4, 6, +, *, 4, 9, 3, /, +, * is?

a) 600
b) 350
c) 650
d) 588

12. Convert the following infix expressions into its equivalent postfix expressions
(A + B ⋀D)/(E - F)+G

a) (A B D ⋀ + E F - / G +)
b) (A B D +⋀ E F - / G +)
c) (A B D ⋀ + E F/- G +)
d) None

ANSWER: a) (A B D ⋀ + E F - / G +)

13. Convert the following Infix expression to Postfix form using a stack

x + y * z + (p * q + r) * s, Follow usual precedence rule and assume that the expression is legal.

a) xyz*+pq*r+s*+
b) xyz*+pq*r+s+*
c) xyz+*pq*r+s*+
d) none

14. Which of the following statement(s) about stack data structure is/are NOT correct?

a) Stack data structure can be implemented using linked list
b) New node can only be added at the top of the stack
c) Stack is the FIFO data structure
d) The last node at the bottom of the stack has a NULL link

ANSWER: c) Stack is the FIFO data structure

15. Consider the linked list implementation of a stack. Which of the following node is considered as Top of the stack?

a) First node
b) Last node
c) Any node
d) Middle node

16. Consider the following operation performed on a stack of size 5.
Push(1);
Pop();
Push(2);
Push(3);
Pop();
Push(4);
Pop();
Pop();
Push(5);

After the completion of all operation, the no of element present on stack are

a) 1
b) 2
c) 3
d) 4

17. Which of the following is not an inherent application of stack?

a) Reversing a string
b) Evaluation of postfix expression
c) Implementation of recursion
d) Job scheduling

18. Which of the following operation take worst case linear time in the array implementation of stack?

a) Push
b) Pop
c) IsEmpty
d) None

19. The type of expression in which operator succeeds its operands is?

a) Infix Expression
b) pre fix Expression
c) postfix Expression
d) None

20. Which of the following application generally use a stack?

a) Parenthesis balancing program
b) Syntax analyzer in compiler
c) Keeping track of local variables at run time
d) All of the above

ANSWER: d) All of the above

21. Consider the following array implementation of stack:

#define MAX 10
Struct STACK
{
Int arr [MAX];
Int top = -1;
}

If the array index starts with 0, the maximum value of top which does not cause stack overflow is?

a) 8
b) 9
c) 10
d) 11

22. What is the minimum number of stacks of size n required to implement a queue of size n?

a) One
b) Two
c) Three
d) Four

23. Assume that the operators +,-, X are left associative and ⋀ is right associative. The order of precedence (from highest to lowest) is ⋀, X, +, -. The postfix expression corresponding to the infix expression a + b X c – d ⋀ e ⋀ f is

a) abc X+ def ⋀ ⋀ -
b) abc X+ de⋀f⋀ -
c) ab+c Xd – e ⋀f⋀
d) -+aXbc⋀ ⋀def

ANSWER: a) abc X+ def ⋀ ⋀ -

24. If the elements “A”, “B”, “C” and “D” are placed in a stack and are deleted one at a time, in what order will they be removed?

a) ABCD
b) DCBA
c) DCAB
d) ABDC

25. Consider the usual implementation of parentheses balancing program using stack. What is the maximum number of parentheses that will appear on stack at any instance of time during the analysis of ( ( ) ( ( ) ) ( ( ) ) )?

a) 1
b) 2
c) 3
d) 4

#### Discussion

• RE: MCQs on stacks with answers -Yogesh Sonawane (03/21/21)
• I think answer of 21st question should be 9.
• RE: MCQs on stacks with answers -yogeswararao (10/13/19)