arvin check my comments https://gateoverflow.in/1061/gate2004-67
Control word = conditional flag bits + controls signal + next micro instruction address
24 = 4 + 8 + next micro instruction address
=> next micro instruction address= 24-12=12.
Hence there are 212 micro instructions in the control memory.
Each of the micro instructions occupy 24 bits i.e. one control word for each of them.
So total size of control memory = control word size* no. of micro instructions = 24 bits * 212 = 3B * 212= 3*4 * 210 B = 12 KB.