Page 660 - Computer science 868 Class 12
P. 660
COMPUTER SCIENCE
SAMPLE PAPER (SOLVED)
(THEORY)
(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.
Indicate briefly your working and reasoning, wherever required.
Question 1.
(i) The law which states a+ b.c=(a+b).(a+c) is [1]
(a) Idempotent Law (b) Distributive Law
(c) De Mogran’s Law (d) Complement Law
Ans. (b) Distributive Law
(ii) Assertion: An SOP can be in Canonical SOP form in which each product term contains all literals. [1]
Reason: Each product term is actually the maxterm.
(a) Both Assertion and Reason are true, and Reason is the correct explanation for Assertion.
(b) Both Assertion and Reason are true, but Reason is not the correct explanation for Assertion.
(c) Assertion is true and Reason is false.
(d) Assertion is false and Reason is true.
Ans. (c) An SOP can be in Canonical SOP form in which each product term contains all literals. So, these product terms are actually
the minterms. Hence, the canonical SOP form is also called as the sum of minterms form.
(iii) Converse of conditional b'→a is [1]
(a) a → b' (b) a → b
(c) b → a' (d) b' → a
Ans. (a) a → b'
(iv) If A=0, B=1, C=1 and D=0 then its minterm is [1]
(a) A'.B.C.D' (b) A.B'.C'.D
(c) A+B'+C'+D (d) A'+B+C+D'
Ans. (a) A'.B.C.D'
(v) If class B is subclass of class A then which is the correct syntax to declare B. [1]
(a) class B : A (b) class B sub A
(c) class A extends B (d) class B extends A
Ans. (d) class B extends A
(vi) Write the canonical sum of product form of the function F(A,B+C)= A'.B'+B.C [1]
Ans. A'.B'.1 + B.C.1
= A'.B'.(C+C') + B.C.(A+A')
= A'.B'.C+A'.B'.C'+A.B.C+A'.B.C
(vii) Assertion: NOR gate is the complement of the OR gate. [1]
Reason: NOR gate produces high output (1) only when all inputs are low (0).
(a) Both Assertion and Reason are true, and Reason is the correct explanation for Assertion.
(b) Both Assertion and Reason are true, but Reason is not the correct explanation for Assertion.
658658 Touchpad Computer Science-XII

