For a 2 input nor gate,there are 4 possible combinations,so we can implement it using 4 x 1 multiplexer.The two inputs A and B are given to the mux as selection inputs and keeping enable signal high.
Now for 2 input nor gate the output will be 1 when all inputs are 0.,thus we will connect Vcc to I0 and ground to I1,I2 and I3.
Hi p_shinde
Look what a nor gate does.Assume A and B are inputs.
If B zero it passes the (A complement) to output.
if B is one then output is '0'.
Now connect B to select
A' to LSB input
and logic 1 to MSB input