Boolean Algebra & Logic Gates MCQ [Free PDF] – 3 Objective Questions with Answers

Boolean algebra has operation-specific laws. AND and OR satisfy commutative and associative laws; XOR also satisfies commutative and associative laws, although it is not idempotent (A⊕A=0). Key relation: NAND universality: NOT A=A NAND A; AND from double NAND; OR via De Morgan. XOR associativity: A⊕B⊕C is independent of grouping.

Exam focus: Do not confuse XOR’s non-idempotent property with associativity. Common trap: Assuming XOR is non-associative because its output changes with parity.

Boolean algebra provides identities such as absorption, De Morgan’s laws and distributive rules that systematically reduce a logic expression and therefore the required gate count. Truth tables verify equivalence, but they are not the primary algebraic reduction method.

Boolean algebra uses exact identities for logic simplification. De Morgan transforms complemented sums/products, while absorption removes redundant terms; care is needed because A+A'B simplifies to A+B, not A. Key relation: (A+B)'=A'B'; A+AB=A; A+A'B=A+B.

Exam focus: Test a doubtful identity with a two-row truth assignment. Common trap: Absorption identities with a complemented term are easy to misremember.