PSC HSST Computer Science Model Questions and Answers – Part 5

51. 1+4+7+……+(3n-2) is:
(A) 3n(n+1)/2 (B) n(3n-1)/2
(C) n(2n-1)/2 (D) n(3n+1)
Answer: B

52. Which among the following functions is not reflexive?
(A) The relation Ü on the set Z of integers
(B) Set inclusion Í on a collection C of sets
(C) Relation ^ (perpendicular) on the set of lines L in a plane
(D) Relation || on a set of lines L in a plane
Answer: C

53. Which of the following type of relations partitions a set into a set of disjoint classes?
(A) partial ordering (B) equivalence
(C) reflexive (D) symmetric
Answer: B

54. How many times in nPr that of nCr?
(A) r! (B) n!
(C) (n-r)! (D) n*r
Answer: A

55. Deterministic and non-deterministic models of which among the following automata have non-equivalent powers?
(A) FA B) PDA
(C) LBA (D) TM
Answer: A

56. Which among the following types of languages are accepted both by Finite Automata and Push down automata?
(A) Regular (B) context free
(C) Context sensitive (D) none of the above
Answer: D

57. Consider the following two languages over {a, b}.
L1- the set of strings beginning and ending with an a
L2- the set of strings with same number of a’s and b’s
Which of the following is true about L1 and L2?
(A) L1 and L2 are both regular
(B) L1 is regular and L2 is context-free but not regular
(C) Neither L1 nor L2 is regular, but both are context-free
(D) L1 is context free but not regular and L2 is not context free
Answer: B

58. Classify into one of the alternatives the grammar denoted by the productions S→aB, S→bA, A→a, A→aS, A→bAA, B→b, B→bS, B→aBB, AB→BA :
(A) Regular Grammar (B) Context free grammar
(C) Context sensitive grammar (D) Unrestricted Grammar
Answer: C

59. ~q˅p is equivalent to:
(A) ~p→q (B) q→p
(C) ~p→~q (D) ~q→~p
Answer: B

60. CRC is:
(A) an error detection code
(B) an error correction code
(C) an error detection and correction code
(D) none of these
Answer: A

61. Totempole output is characteristic of the logic IC family:
(A) RTL (B) CMOS
(C) TTL (D) IIL
Answer: C

62. A XOR B is equivalent to:
(A) (A+B).(B’+A’) (B) A’B’+BA
(C) AB+B’A’ (D) (A+B’).(B’+A)
Answer: D

63. Which of the following is not correct?
(A) (x+y)’=x’.y’ (B) (x’+y’)’=x.y
(C) (x’.y’)’=x+y (D) (x’+y’)’=x’.y’
Answer: D

64. Which among the following flip-flops is a modification to the R-S flip-flop that avoids its indeterminate state?
(A) JK flip-flop (B) D flip-flop
(C) Q flip-flop (D) T flip-flop
Answer: B

65. The decimal equivalent of the octal number 137 is:
(A) 85 (B) 87
(C) 95 (D) 97
Answer: C

66. The next larger integer corresponding to the positive integer whose representation in hexadecimal format is FF, represented in octal form is:
(A) 1000 (B) 100
(C) 177 (D) 200
Answer: 174
Explanation:
FF in binary form = 1111 1111
Its decimal value = 255
Next larger integer in Decimal = 256
Its corresponding octal number = 174

67. Into which of the following categories of tokens can you classify the character stream “elseif”?
(A) keyword (B) identifier
(C) reserved word (D) none of these
Answer: C

68. How many C tokens are present in the following assignment statement a+=b;
(A) 2 (B) 3
(C) 4 (D) 5
Answer: C

69. The operator in C among the following that is not overloaded is:
(A) * (B) /
(C) + (D) –
Answer: B

70. The incorrect statement a++b++ in C can be converted to a legal statement by changing which of the + characters to =?
(A) 1st alone (B) 2nd alone
(C) 1st or 2nd (D) 1st or 2nd alone but not both
Answer: B

71. Which of the following is a valid operator of C++ but not of C?
(A) New (B) ++
(C) — (D) →
Answer: A

72. An abstract class in C++ is:
(A) a class with no data members
(B) a class with no member functions
(C) a class declared with virtual qualification
(D) used to provide a standard interface for derived classes
Answer: C

73. In a publicly derived subclass, the protected members of a superclass are:
(A) available with public visibility
(B) available with protected visibility
(C) available with private visibility
(D) not available
Answer: B

74. Which among the following DMLs given below is a domain calculus language?
(A) SQL (B) QUEL
(C) QBE (D) SEQUEL
Answer: A

75. A relation in BCNF with no multivalued dependencies is in:
(A) 1NF (B) 2NF
(C) 3NF (D) 4NF
Answer: D