ISC MCQ computer science sample papers free download

ISC Class 12 Sample Paper 1 Computer Science-Half yearly Class: XII A,XII B Marks: 70 - Test Start: 24-09-2021 10:00 am - Test End: 24-09-2021 11:00 am - Duration: 105 mins 1) The combination circuit which adds three binary digits (1) Answer a) Full Adder b) Half Adder c) Decoder d) Multiplexer 2) The expression A+AB=A represents which boolean law (1) Answer a) Absorption b) Associative c) Distributive d) Commutative 3) The dual of x.y+z=x.y+x.z is (1) Answer a) x+y.z=x+y.x+z b) (x+y)z=x+y.x+z c) x(y+z)=x.y+x.z 4) If A=1,B=1,C=0,D=0,the maxterm is (1) Answer a) A'+B'+C+D b) A'B'CD c) A+B+C'+D' d) ABC'D' 5) The complement of the boolean expression F(P,Q,R)=P'Q+QR'+PR (1) Answer a) (P+Q').(Q'+R).(P'+R') b) (P'+Q).(Q'+R).(P'+R') c) (P'+Q).(Q'+R).(P+R) d) (P+Q').(Q+R').(P'+R') 6) The boolean expression for output F=x.y.z'.This is ____form (1) Answer a) SOP b) POS c) None of the above 7) NOR gate is a combination of (1) Answer a) NOT and OR b) AND and OR c) NOT and XOR 8) The pair group in a 3 input K-map eliminates (1) Answer a) 1 variable b) 2 variables c) 3 variables 9) The proposition a+a'b=a+b is based on___law (1) Answer a) Distributive b) Associative c) Conditional Elimination 10) Application of ______ is parallel to serial conversion (1) Answer a) Multiplexer b) Decoder c) Adder 11) If the input in a decoder is ABC'D ,then the decimal output is (2) Answer a) 1101 b) 10 c) 1010 12) An array ARR[10][5] is stored in memory with each element requiring 2 bytes of storage.If the first element ARR[0][0] is (2) stored at the location 1250, calculate the location of ARR[5][3]when the array is stored row major wise. Answer a) 1306 b) 1290 c) 1250 13) If (A=>B'),then it's contrapositive is (1) Answer a) B=>A' b) B'=>A c) B'=>A' 14) With reference to Q 13,find the converse of the expression (1) Answer a) B'=>A b) A'=>B c) B=>A' 15) Reduce the boolean expression AB+A(B+C)+B(B+C) (2) Answer a) B+AC b) AB c) AB+C 16) The boolean expression F=x'y+xy' represents a XOR gate (2) Answer a) True b) False 17) The output of System.out.println("Number:"+4+2); (2) Answer a) Number:42 b) Number:6 18) The output of System.out.println('c'+'6'+'A'); (2) Answer a) 218 b) 170 c) None of the above 19) How many times will the loop execute? int x=2,y=50; do {++x; y--=x++; }while(x<=10); return y; (2) Answer a) 5 b) 9 c) None of the above 20) The conditional statement used to calculate the sum of all elements except the diagonal element,where I and j are row (2) and column index for a matrix of size 4x4 Answer a) (i!=j && (i+j)!=3) b) (i!=j || (i+j)!=3) c) (i==j &&(i+j)!=4) 21) The boolean expression p.q+p.q' is a (2) Answer a) Contigency b) Tautology c) Contradiction 22) Reduce F(A,B,C,D)=∑(4,6,7,10,11,12,14,15) using K-map.What will be the least number of groups and their types? (1) Answer a) 3 quads b) 2 quads 2 pairs c) 2 quads 1 pair 23) With reference to Q.22,reduce the expression of the boolean function. (2) Answer a) BC+AC+BD' b) BC+AC+BC'D' c) BC+AC+B'D 24) Reduce X(A,B,C,D)=π(2,3,4,5,12,14) using K-map.What will be the least number of groups and their types? (1) Answer a) 3 pair b) 1 quad 2 pair c) 1 quad 1 pair 25) With reference to Q.24,reduce the expression of the boolean function. (2) Answer a) (A'+B'+C).(A'+B+C').(A+B+D') b) (A'+B'+C).(A'+B).(A+B+D') c) (A'+B+C').(A+D') 26) A combinational circuit with three inputs A,B,C detects an error during transmission of code and give the output D as 1 (2) if any two of the inputs are low (0). The SOP expression of the above will be Answer a) A'B'C+A'BC'+AB'C' b) ABC+A'B'C'+A'BC' c) ABC+A'BC+AB'C 27) With reference to Q.26, what is the maximum input combination for the above truth table (1) Answer a) 8 b) 16 c) 4 28) (1) From the logic diagram given where x,y,z are the inputs, write the expression at (1) Answer a) x+y' b) x+y c) (x+y)' 29) With reference to Q.28,write the expression at (3) (1) Answer a) xz.(x+y') b) xy'+(x+z) c) xy'+xz 30) With reference to Q.28,write the reduced form of expression F(x,y,z) (1) Answer a) x+z' b) xz c) xz' 31) Find the complement of F=x'+xy' (2) Answer a) xy b) 0 c) xy' 32) With reference to Q.31, name the basic law used for the complement (1) Answer a) De-morgan's law b) Complement law c) Distributive law 33) With reference to the program code given below,state the value of p when x=36,y=20 public void calc(int x, int y) (2) { int p=1; for(int I=1;I<=x && I<=y;I++) { if(x%I==0 && y%I==0) p=I;. break; } } Answer a) 4 b) 8 c) 2 34) With reference to Q 33,what is the function performing? (1) Answer a) GCD of 2 numbers b) LCM of 2 numbers c) Factors of 2 numbers 35) With reference to the program code,state the value of s,when n=55 (2) public void chk(int n) { s= n; while(s>9) { n=s;s=0; while(n>0) { a=n/10; b=a*10; c=n-b; s=s+c; n=a; }} Answer a) 1 b) 0 c) None of the above 36) With reference to Q 35,what is the function chk( ) performing? (1) Answer a) Finding magic number b) Finding evil number c) Finding Smith number 37) With reference to the program code, find the values of s if num[ ]={14,20,18} (2) public void display( int num[ ]) { for( i=0;I<3;i++) { s=0; { for(j=1 ;j<=num[i] ;j++) { if num[ i]%j==0) s =s+j; } System.out.print(s+" "); }} Answer a) 24 42 39 b) 20 42 35 c) 24 40 35 38) With reference to Q 37,what is the display( ) performing? (1) Answer a) Sum of the factor of each element b) Sum of the factorial of each element c) sum of even factor of each element 39) With reference to the program code,find the value of x (2) int x=0; do { if(x<3) { x+=2; System.out.println(x); continue; } else { System.out.println(++x); break; } }while(x<10); Answer a) 2 4 5 b) 2 3 4 c) 2 4 6 40) With reference to Q 40,state the function of break. (1) Answer a) Come out of the iteration b) Skip an iteration c) Continue the iteration 41) With reference to the program code,state the output (2) int x=10,y=5,z=0; if(x>y||x==y) z=++x+--y; System.out.println(z+" "+x +" "+y); Answer a) 15 11 4 b) 11 4 15 c) 14 10 4 42) When a member is declared static,it can be accessed before any objects of its class are created. (1) Answer a) True b) False 43) The following function is a part of some class. It sorts the array a[ ] in ascending order using insertion sort technique. (1) There are some places in the code marked by (1)(2)(3)(4)(5) which must be replaced by expression or statement so that the function works correctly. void insertsort( int a[ ]) { int m=(1); int b,i,t; for( i= (2);i<m;i++) { t=a[ i]; b= i-1; while( (3)>=0 && t<a[ b]) { a[ b+1]=a[ b]; (4); } (5)=t; }} What is the expression/statement at (1)? Answer a) a.length b) 0 c) 1 44) With reference to Q 43,what is the expression/statement of (2)? (1) Answer a) 1 b) 0 c) a.length-1 45) With reference to Q 43,what is the expression/statement at (3)? (1) Answer a) b b) t c) m 46) With reference to Q 43, what is the expression/statement at (4)? (1) Answer a) b-b) b++ c) b=i 47) With reference to Q 43,what is the expression/statement (5)? (1) Answer a) a[b] b) a[i] c) b 48) The following function is a part of some class which checks whether a number is unique or not. There are some (1) places marked as (1)(2)(3)(4)(5) which must be replaced by statement or expression so that the function works correctly. public void unique(int n) { k= n; while(1) { d= (2); c=0; num=k; while(num!=0) { d1= num%10; if(3) c++; (4); } if (c==1) { (5); continue;} else {f=0; break;}} What is expression or statement at (1)? Answer a) n!=0 b) n>0 c) f 49) With reference to Q 48,what is the expression/statement at (2)? (1) Answer a) n%10 b) n/10 c) k%10 50) With reference to Q 48, what is the expression statement at (3)? (1) Answer a) d==d1 b) n==num c) c==f 51) With reference to Q 48, what is the expression statement at(4)? (1) Answer a) num=num/10 b) num=num%10 c) n=n%10 52) With reference to Q 48, what is the expression statement at (5)? (1) Answer a) n=n/10 b) n=n%10 c) num=num%10 ] ―――――――――― Answer Key – ISC Class 12 Sample Paper 2 KEY PAPER 1 - C 2 - C 3 - C 4 - B 5 - B 6 - C 7 - B 8 - B 9 - D 10 - A 11 - B 12 - A 13 - B 14 - D 15 - D 16 - B 17 - (A) - (i) - (B) - (iii) 18 - C 19 - d 20 - b 21 - (a) - (i) (b) - (iii) 22 - (a) - (iii) - (b) - (ii) 23 - (a) - (iii) (b) - (iii) 24 - (a) - (iii) (b) - (iii) (c) - (ii) 25 - (d) 26 - (a) - (i) - (b) - (ii) (c) - (iii) (d) - (iv) (e) - (i) 27 - (a) - (i) (b) - (iv) (c) - (III) (D) - (iii) 28 - (A) - (ii) (B) - (ii) 29 -- (A) - (iii) --- (B) - (III) 30 - (A) - (I) - (C) - (i) 31 - (A) - (II) - B - (III) 32 - (A-E) - (I) ―――――――――― ISC Class 12 Sample Paper 3 The marks intended for questions are given in brackets [ ]. --------------------------------------------------------------------------------------------------------------------- Select the correct option for each of the following questions. --------------------------------------------------------------------------------------------------------------------- 1. The expression for Absorption law is given by _________ . [1] a) A + AB = A b) A + AB = B c) AB + AA’ = A d) A + B = B + A 2. According to boolean law: A + 1 = ? [1] a) 1 b) A c) 0 d) A’ 3. The involution of A is equal to _________ [1] a) A’ b) A c) 1 d) 0 4. A(A + B) = ? [1] a) AB b) 1 c) (1 + AB) d) A 5. DeMorgan’s theorem states that _________ [1] a) (AB)’ = A’ + B’ b) (A + B)’ = A’ * B c) A’ + B’ = A’B’ d) (AB)’ = A’ + B 7. The statement (~P<->Q)∧~Q is true when? [1] a) P: True Q: False b) P: True Q: True c) P: False Q: True d) P: False Q: False 8. If P is always against the testimony of Q, then the compound statement P→(P v ~Q) [1] is a __________ a) Tautology b) Contradiction c) Contingency d) None of the mentioned 9. What is the dual of (A ∧ B) v (C ∧ D)? [1] a) (A V B) v (C v D) b) (A V B) ^ (C v D) c) (A V B) v (C ∧ D) d) (A ∧ B) v (C v D) 10. ~ (A ∨ q) ∧ (A ∧ q) is a ___________ [1] a) Tautology b) Contradiction c) Contingency d) None of the mentioned 11. The contrapositive of p → q is the proposition of ____________ [2] a) ~p → ~q b) ~q → ~p c) q → p d) ~q → p 12. Decoder is constructed from ________________. [2] a) Inverters b) AND gates c) Inverters and AND gates d) None of the mentioned 15. A universal logic gate is one which can be used to generate any logic function. [2] Which of the following is a universal logic gate? a) OR b) AND c) XOR d) NAND 16. A full adder logic circuit will have __________ [2] a) Two inputs and one output b) Three inputs and three outputs c) Two inputs and two outputs d) Three inputs and two outputs 17. The gates required to build a half adder are __________ [2] a) XOR gate and NOR gate b) XOR gate and OR gate c) XOR gate and AND gate d) XNOR gate and AND gate 18. Exclusive-OR (XOR) logic gates can be constructed from what other logic gates? [2] a) OR gates only b) AND gates and NOT gates c) AND gates, OR gates, and NOT gates d) OR gates and NOT gates 19. (X+Y')(X+Z) can be represented by _____ [2] a) (X+Y'Z) b) (Y+X') c) XY' d) (X+Z') 22. Reduce the given Boolean function F(A,B,C,D) = ∑(1,3,5,7,8,9,10,11,14,15) by using 4variable Karnaugh map and answer the following questions: (a) What will be the least number of groups and their types formed for reduction? [1] (i) 6 pairs (ii) 2 quad and 2 pairs (iii) 1 quad and 3 pairs (iv) 3 quads (b) The reduced expression of the Boolean function given above is: [2] (i) ACD’ + B’D’ + BD (ii) (A+C’+D’).(B’+D’).(A+C’) (iii) A’D+AC+AB’ (iv) (C+D’). (B’+D’).(A+B+D) 23. Reduce the given Boolean function F(A,B,C,D) = π(0,1,2,4,5,6,8,10) by using 4-variable Karnaugh map and answer the following questions: (a) What will be the least number of groups and their types formed for reduction? [1] (i) 6 pairs (ii) 3 quads (iii) 1 quad and 3 pairs (iv) 2 quad and 3 pairs (b) The reduced expression of the Boolean function given above is: [2] (i) (A+C).(A+D).(B+D) (ii) BC + BD + A’D (iii) AB’ + C’D’ + B’D’ (iv) (A+B’).(C’+D’).(B’+D’) 24. Convert the following SOP expression into canonical sop expression. [2] F(A,B) = A’ + AB Canonical sop expression will be a) A’B + A’B’ +AB b) AB + A’B’ + AB’ c) A’B + AB’ + AB d) A’B + A’B’ +A’B D : Record of literary skills Output: R : Denotes eligible to apply [ 1 indicates Yes and 0 indicates No in all cases] Draw the truth table for the inputs and outputs given above and answer the following questions: (a) The SOP expression for R(A,B,C,D) will be: [2] (i) F(A,B,C,D)= ∑ (3, 5, 7, 11, 12, 13, 14, 15) (ii) F(A,B,C,D)= π (0, 1, 2, 3, 4, 5, 8, 9, 10, 12, 13) (iii) F(A,B,C,D)= π (0, 1, 2, 3, 4, 10,11) (iv) F(A,B,C,D)= ∑ (6, 7, 11, 14, 15) (b) The maximum input combinations for the above truth table will be: [1] (i) 24 (ii) 16 (iii) 8 (iv) 4 26. A matrix A[m][n] is stored with each element requiring 4 bytes of storage. [2] If the base address at A[1][1] is 1500 and the address at A[4][5] is 1608, determine the number of rows of the matrix when the matrix is stored in Column Major Wise. a) 5 b) 6 c) 7 d) 8 27. Give the output: [2] public class A { public static void main(String[] args) { System.out.println('j' + 'a' + 'v' + 'a'); } } a) java b) 418 c) 1069711897 d) ERROR void main () { int result, x ; x=1; result = 0; while (x < = 10) { if (x%2 == 0) result + = x ; ++x; } System.out.println(result) ; } } a) 55 b) 30 c) 25 d) 35 30. Give the output: [2] class output { public static void main(String args[]) { String c = " Hello World "; String s = c.trim(); System.out.println("\""+s+"\""); } } a) “”Hello World”” b) “”Hello World” c) “Hello World” d) Hello world 31. Method overloading is one of the ways that Java supports ………… [1] a) encapsulation b) class c) inheritance d) polymorphism n=n/10; } System.out.println(“Norm = “ + (?4?)_____________); } (a) [1] i) 1.0 ii) 0 iii) 1 (b) [1] i) n>0 ii) n<0 iii) n>1 (c) [1] i) s+d*d ii) s*d+d iii) s*s+d (d) [1] i) Math.sqrt(s) ii) Math.SQRT(s) iii) Math.sqrt(n) { if(min>a[j]) { ?3? = j; min == ?4?; } } t=a[minpos]; a[minpos]=a[i]; a[i]== ?5?; } for( int k=0;k<a.length;k++) System.out.println( a[k ]) ; } (a) [1] i) a.length ii) a.length() iii) a.length-1 (b) [1] i) 0 ii) 1 iii) i+1 (c) [1] i) minpos ii) i iii) min (d) [1] i) a[i] ii) a[j] iii) a[j+1] (e) [1] i) a[j] ii) t iii) a[minpos] nn/=10; if(d==i) { newn=newn*10+d; } } } return newn; } (a) What is returned by the method number() when the value of n=4738? [2] (i) 8374 (ii) 8743 (iii) 3478 (iv) 22 (b) What is the method number() performing? [1] (i) Reversing the digits of a number (ii) Arranging the digits in descending order (iii) Arranging the digits in ascending order (iv) Finding the sum of the digits 35. With reference to the program code given below, answer the questions that follow: void test(int n) { int i=2; while(i<=n) { while(n%i==0) { System.out.print(i+" "); n/=i; } i++; } } 36. With reference to the program code given below, answer the questions that follow: int compute(int a,int b) { int l=Math.max(a,b); int s=Math.min(a,b); while(l%s!=0) { int r=l%s; l=s; s=r; } return s; } (a) What is returned by the method compute() when a=45 and b=36? [2] (i) 18 (ii) 1 (iii) 9 (iv) 180 (b) What is the method compute() performing? [1] (i) HCF (ii) LCM (iii) Remainder (iv) Division ―――――――――― Answer Key – ISC Class 12 Sample Paper 3 --------------------------------------------------------------------------------------------------------------------Select the correct option for each of the following questions. --------------------------------------------------------------------------------------------------------------------- 1. a 2. a 3. b 4. d 5. a 6. b 7. a 8. a 9. b 10. b 11. b 12. c 13. b 14. b 15. d 16. d 17. c 18. c 19. a 20. d 21. a 22. a) iv 22. b) iii 23. a) ii 23. b) i 24. a 25. a) iv 25. b) ii 26. b Answers 34. a) iii 34. b) iii 35. a) ii 35. b) ii 36. a) iii 36. b) i