MCQ for ISC computer science
MCQ for ISC computer science: easy ISC Class 12 Computer Science notes with Java examples for students.
MCQ for ISC computer science
Class X MCQ JAVA
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Boolean algebra MCQs with answers
The questions in the image above, as text, with the answer and a short reason for each.
1. Choose the equation for the Absorption law.
- (1) a + ab = a
- (2) a + b = b + a
- (3) (a')' = a
- (4) a + 1 = 1
Answer: (1) a + ab = a. a + ab = a(1 + b) = a·1 = a.
2. Choose the equation for the Commutative law.
Answer: a + b = b + a. The order of the operands does not change the result.
3. Choose the equation for the Involution law.
Answer: (a')' = a. Complementing a variable twice gives back the variable.
4. Choose the equation for the Distributive law.
Answer: a·(b + r) = (a·b) + (a·r). AND distributes over OR, just as multiplication distributes over addition.
5. (A·B)' = A' + B' is a ________.
- (1) De Morgan's law
- (2) Distributive law
- (3) Involution law
- (4) Absorption law
Answer: (1) De Morgan's law. The complement of a product is the sum of the complements. Its dual is (A + B)' = A'·B'.
6. If the final column of a proposition's truth table contains both 0s and 1s, the proposition is termed a ________.
- (1) Tautology
- (2) Contingency
- (3) Contradiction
- (4) Invalid proposition
Answer: (2) Contingency. A tautology is always 1 (true), a contradiction is always 0 (false), and a contingency is a mix of both.
Remember the laws in pairs
Every Boolean law has a dual, obtained by swapping + with · and 0 with 1. For example, the dual of a + ab = a is a·(a + b) = a. Learning each law together with its dual halves the memorising.
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