# ISC Computer Science 2011 Class-12 Previous Year Question Papers Solved

**ISC Computer Science 2011** Class-12 Previous Year Question Paper Solved for practice. Step by step Solutions with Questions of Part-1 and Part-2 (Section-A,B and C). By the practice of** Computer Science 2011 Class-12** Solved Previous Year Question Paper you can get the idea of solving.

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**ISC Computer Science 2011 **Class-12 Previous Year Question Paper Solved

-: Select Your Topics :-

Maximum Marks: 70

Time allowed: 3 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 rest of the answer.
- The intended marks for questions or parts of questions are given in brackets [ ].

**Part – I (20 Marks)**

**Answer all questions.**

**ISC Computer Science 2011 **Class-12 Previous Year Question Paper Solved** **

While answering questions in this Part, indicate briefly your working and reasoning, wherever required.

**Question 1.**

(a) State the two Absorption laws. Verify any one of them using the truth table. [2]
**(b) Reduce the following expression: [2]**

F(A, B, C) = Σ (0, 1, 2, 3, 4, 5, 6, 7)

Also, find the complement of the reduced expression.

(c) Name the logic gate for the following circuit diagram and write its truth table. [2]

(d) Using truth table, verify whether the following is true or false: [2]

(e) If A = 1, B = 0, C= 1 and D = 1 find its: [2]
(i) Maxterm

(ii) Minterm

**Answer 1:**

**Question 2.**

(a) How can we override a method in inheritance? [2]
(b) A square matrix A[m*m] is stored in the memory with each element requiring 2 bytes of storage.

If the base address A[1] [1] is 1098 and the address at A [4] [5] is 1144, determine the order of the matrix A[m × m] when the matrix is stored Column Major wise. [2]
(c) What is Big O notation? [2]
(d) What is an exception? [2]
**(e) Convert the following infix expression to its postfix form: [2]**

a + b * c – d/e

**Answer 2:**

(a) When we extend a class, you can change the behaviour of a method in the parent class. This is called method overriding. This happens when we write in a subclass a method that has the same signature as a method in the parent class.

(b) B = 1098, W = 2, n = m

1144 = 1098 + 2 [m(5 – 1) + (4 – 1)]
⇒ 1144 = 1098 + 8m + 6

⇒ 8m = 40

⇒ m = 5

The order of the matrix is [5 × 5]
(c) Big O is the function with parameter N, where N is usually the size of the input to the algorithm. More the input size, more impact it can have on the growth rate of the algorithm.

(d) An unexpected situation or unexpected error, during program execution, is known as an exception.

(e) (a + b * c – d/e)

**Question 3.**

(a) The following is a part of some class. What will be the output of the function mymethod( ) when the value of the counter is equal to 3? Show the dry run/working. [5]

void mymethod (int counter) { if (counter == 0) System.out. println(” "); else { System.out.println ("Hello" +counter); mymethod (--counter); System.out.println (" " +counter); } }

(b) The following function is a part of some class which computes and returns the greatest common divisor of any two numbers. There are some places in the code marked by ?1?, ?2?, ?3?, ?4? and ?5? which must be replaced by statement/expression so that the function works correctly0

int gcd(int a, int b) { int r. while(?1?) { r = ?2?; b = ?3?; a = ?4? } if (a ==0) return ?5?; else return-1; }

(i) What is the expression or statement at ?1? [1]
(ii) What is the expression or statement at ?2? [1]
(iii) What is the expression or statement at ?3? [1]
(iv) What is the expression or statement at ?4? [1]
(v) What is the expression or statement at ?5? [1]
**Answer 3:**

(b) (i) a * b! = 0

(ii) b

(iii) a

(iv) a%b

(v) r

**Part- II (50 Marks)**

Answer six questions in this part, choosing two questions from Section A, two from Section B and two from Section C.

**Section – A**

**Answer any two questions.**

### Previous Year Question Paper Solved **ISC Computer Science 2011 **Class-12

**Question 4.**

**(a) State the principle of Duality. Give the dual of the following: [3]**

(A’.B) + (C. 1) = (A’ + C).(B + C)

**(b) Reduce the Boolean expressions to their simplest forms: [4]**

(i) {(C.D)’ +A} + A + C.D + A.B

(ii) A. {B + C(A.B + A. C)’}

**(c) Verily using a truth table if: [3]**

**Answer 4:**

(a) According to the principle of Duality, “Dual of one expression is obtained by replacing AND (.) with OR (+) and OR with AND togather with replacement of 1 with 0 and 0 with 1.”

Dual of (A’ . B) + (C.1) is given by (A’ + B). (C + 0) = (A’ + B). C

Dual of (A’ + C). (B + C) is given by (A’.C) + (B.C)

Then Dual of (A’ . B) + (C . 1) = (A’ + C) . (B + C) is (A’ + B). (C + 0) = (A’.C) + (B.C)

(b)

(i) {(C.D)’ + A) + A + C. D + A.B

= {(C.D)’ + A} + A + AB + C.D

= {(C.D)’ + A) + A + C.D [Absorption Law]
= (C’ + D’) + A + A + C.D [De Morgan’s Theorem]
= C’ + D’ + A + C.D

= C’ + C”.D + D’ + A

= C’ + D + D’ + A

= C’ + A

(ii) A. {B + C (A . B + A. C)’}

= A {B + C ((A.B)’ . (A.C)’)} [De Morgan’s theorem]
= A. {B + C ((A’ + B’). (A’ + C’))} [De Morgan’s theorem]
= A. {B + C(A’+B’C’)} [Distributive law]
= A. {B + C.A’ + B’.C’.C.}

= A. (B + C.A’ +0) [Complement property]
= AB + C.A’.A [Complement property]
= AB + 0

= AB

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