ISC Class 12th Computer Science Question Paper and Answer Key 2025: FREE PDF Download

ISC Class 12th Computer Science Question Paper and Answer Key 2025: The ISC Class 12 Computer Science Exam 2025 was conducted on March 24, 2025, with the help of the Council for the Indian School Certificate Examinations (CISCE). This exam plays an important role in the academic journey of the students, testing their understanding of the subject of computer science. 

ISC Class 12 Computer Science 2025 Exam Overview

Exam Date: [24th March, 2025]

Subject Code: [208]

Exam Duration: 3 Hours

Maximum Marks: 70

ISC Class 12th Computer Science Exam Pattern 2025

ISC Class 12 Computer Science Question Paper 2025

Students can download the ISC Class 12 Computer Science question paper PDF from the link below. This question paper is important for those candidates who want to take up the course in Computer Science after their class 12th exams. Students can check the question paper below and can also download the link for free. 

ISC Class 12 Computer Science Answer Key 2025

Students must be eagerly waiting to check their answers after giving the exam. Well, here, we are providing the answer key as well as the question paper. Students can check their answers and can also calculate their estimated score.

Question 1

(i) The complement of the Boolean expression (A ⋅ B') + (B' ⋅ C) is:

(a) (A + B') ⋅ (B' + C)
(b) (A' + B') ⋅ (B + C')
(c) (A' + B) ⋅ (B + C')
(d) (A ⋅ B') + (B ⋅ C')

Correct Answer: (b) (A' + B') ⋅ (B + C')

(ii) Given below are two statements marked, Assertion and Reason. Read the two statements carefully and choose the correct option.

Assertion: The expression ~(X ∨ Y) is logically equivalent to (~X ∧ ~Y)

Reason: The commutative property of logical operators states that the order of the operands does not change the result of a binary operation.

(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) Both Assertion and Reason are false.

Correct Answer: (c) Assertion is true and Reason is false.

(iii) According to the Principle of Duality, the Boolean equation (1 + Y) ⋅ (X + Y) = Y + X' will be equivalent to:

(a) (1 + Y') ⋅ (X' + Y') = Y' + X
(b) (0 + Y) ⋅ (X + Y) = Y ⋅ X'
(c) (0 + Y) ⋅ (X + Y) = Y + X'
(d) (1 ⋅ Y) + (X ⋅ Y) = Y ⋅ X'

Correct Answer: (c) (0 + Y) ⋅ (X + Y) = Y + X'

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(iv) The Associative Law states that:

(a) A ⋅ B = B ⋅ A
(b) A + B = B + A
(c) A ⋅ (B + C) = A ⋅ B + A ⋅ C
(d) A + (B + C) = (A + B) + C

Correct Answer: (d) A + (B + C) = (A + B) + C

(v) Consider the following code statement:

public class Person
{
int age;

public Person (int age)
{
this.age = age;
}
}

Which of the following statements are valid for the given code?

I. The keyword this in the constructor refers to the current instance of the class.

II. The keyword this differentiates between the instance variable age and the parameter age.

III. The keyword this can be used only in constructors.

(a) Only I and II
(b) Only II and III
(c) Only I and III
(d) Only III

Correct Answer: (a) Only I and II

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(vi) Given below are two statements marked, Assertion and Reason. Read the two statements carefully and choose the correct option.

Assertion: The break statement prevents fall through effect in the switch case construct.

Reason: The break statement enables an unnatural exit from the loop.

(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) Both Assertion and Reason are false.

Correct Answer: (c) Assertion is true and Reason is false.

(vii) The canonical expression of F(P, Q, R) = π(2, 5, 7) is:

(a) (P + Q' + R) ⋅ (P' + Q + R') ⋅ (P' + Q' + R')
(b) (P ⋅ Q' ⋅ R') + (P' ⋅ Q ⋅ R') + (P' ⋅ Q' ⋅ R)
(c) (P' + Q' + R') ⋅ (P' + Q' + R) ⋅ (P + Q + R)
(d) (P ⋅ Q' ⋅ R') + (P ⋅ Q' ⋅ R) + (P' ⋅ Q ⋅ R)

Correct Answer: (b) (P ⋅ Q' ⋅ R') + (P' ⋅ Q ⋅ R') + (P' ⋅ Q' ⋅ R)

(viii) Study the given propositions and the statements marked, Assertion and Reason that follow it. Choose the correct option on the basis of your analysis.

P – It is a holiday
Q – It is a Sunday

Assertion: If it is not a Sunday, then it is not a holiday. (Q' ⇒ P')

Reason: Inverse is formed when antecedent and consequent are interchanged.

(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) Both Assertion and Reason are false.

Correct Answer: (c) Assertion is true and Reason is false.

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(ix) For the given code segment, write Big O notation for worst-case complexity.

for (int i = 1; i <= P; i++)
{
// Statements
for (int j = 1; j <= P; j++)
{
for (int k = 1; k <= Q; k++)
{
// Statements
}
}
}

Correct Answer: O(P²⋅Q)

(x) Write the minterms in canonical form for the Boolean Function X(A, B), from the truth table given below: [1]

Correct Answer: The minterms correspond to the rows where X = 1:
Canonical form: X(A, B) = A'B' + AB

Other Related Links

• ISC 12th Specimen Papers 2025

• CISCE Date Sheet 2024-25