Page 678 - Computer science 868 Class 12
P. 678
ISC SPECIMEN QUESTION PAPER
(THEORY)
Maximum Marks: 70 Time Allowed: Three Hours
(Candidates are allowed additional 15 minutes for only reading the paper.
They must NOT start writing during this time).
Answer all questions in Part I (compulsory) and six questions from Part-II,
choosing two questions from Section-A, two from Section-B and
two from Section-C.
All working, including rough work, should be done on the same sheet as the
The intended marks for questions or parts of questions are given in brackets [ ].
PART I (20 Marks)
Answer all questions.
While answering questions in this Part, indicate briefly your working and reasoning,
wherever required.
Question 1.
(i) Which Boolean law states (A+B).A=A [1]
(a) Distributive (b) Commutative
(c) Absorption (d) Associative
(ii) Assertion: XNOR gate is complement of XOR gate [1]
Reasoning: Because applying De Morgan’s Law we get (A'.B+AB')' = (A+B').(A'+B)
Which of the following options is correct?
(a) Both Assertion and Reasoning are true and Reasoning is the correct explanation of Assertion
(b) Both Assertion and Reasoning are true but Reasoning is not the correct explanation of Assertion
(c) Assertion is true but Reasoning is false
(d) Both Assertion and Reasoning is false
(iii) Assertion: If A=“It is cloudy” B=“It will rain” [1]
then converse of the conditional is “If it is not cloudy then it will not rain”
Reasoning: Inverse of a conditional is obtained by interchanging negated antecedent and negated consequent
Which of the following options is correct ?
(a) Both Assertion and Reasoning are true and R is the correct explanation for A
(b) Both Assertion and Reasoning are true and R is not the correct explanation for A
(c) Assertion is True but Reasoning is False
(d) Assertion is false but Reasoning is True
(iv) The dual of the Boolean expression (X.Y)'+X'.Y'.0=(X.Y)' is [1]
(a) (X+Y)'.(X'+Y'+1)= (X+Y)' (b) (X+Y)'.(X'+Y') +1 = (X+Y)'
(c) (X+Y).(X+Y+1)=(X+Y) (d) (X+Y)'.(X'+Y').0= (X+Y)'
(v) If A=0 B=1 C=1 D=1 then its maxterm is [1]
(a) A+B'+C'+D (b) A.B'.C'.D
(c) (A'+B+C+D') (d) A'.B.C.D'
(vi) The complement of the boolean expression is X.Y’.Z+X.Y+Y.Z’ is [1]
(a) (X+Y+Z).(X'+Y').(Y'+Z) (b) (X'+Y+Z').(X'+Y').(Y'+Z)
(c) (X'+Y+Z').(X+Y).(Y'+Z) (d) (X+Y+Z).(X'+Y').(Y+Z')
(vii) What is the use of continue statement in a loop. [1]
(viii) Why variables are called identifiers. [1]
676676 Touchpad Computer Science-XII

