Question 4: Construct a 16 x 1 multiplexer with two 8 x 1 and one 2 x 1 multiplexers. Use block diagrams. Question 5: Design a combinational circuit that converts 4-bit binary code into 4-bit gray code. Question 6: Design a half-subtractor and a full subtractor circuit. Question 7: Implement the following Boolean function with a multiplexer F(A, B, C, D) = {m(0,1,3,4,8,9,15) Question 8: An 8x1multiplexer has inputs A, B, and C connected to the selection inputs S2, S, and So, respectively. The data inputs lo through 17, are as follows: 11 = 12 = 17 =0; 13 = ls =1; lo = 14 = D; and lo= D'. Determine the Boolean function that the multiplexer implements