Question

Figure shows combination of gates. For Y = 1 which of the following options is correct.

(1) A = 0, B = 1

(2) A = 1, B = 1

(3) A = 1, B = 0

(4) A = 0, B = 0

Answer 1

(3) A = 1, B = 0

For A = 1, B = 0; the output of gate 1 (i.e. OR gate) C₁ = 0. The output of gate C₂ (i.e. NAND gate) C₂ = 0. C₁ = 0 and C₂ = 0 are input of gate 3 which is NOR gate, hence outout Y = 1.