Design the full adder circuit as given in the theory section. The circuit should take 3 inputs (A, B, and Cin) and produce 2 outputs (Sum and Carry).

Construct a 4-bit binary adder using 4 full adders. Given two 4-bit binary numbers A₃A₂A₁A₀ and B₃B₂B₁B₀, the circuit should output S₃S₂S₁S₀ and Cout which is the final carry. For circuit diagram, refer to the theory section.

Design a 3-bit full subtractor using XOR, AND, OR, and NOT gates. Given X, Y, and Z, the circuit should output D (difference) and B (Borrow). D = X ⊕ Y ⊕ Z and B = X'.Y + Y.Z + X'.Z

Can the final OR gate in the Full Adder circuit (given in the theory section) be replaced by an XOR gate? If yes, why? If no, why not?