Minimum number of comparisons required to sort 5 elements

If the binary tree in figure is traversed in inorder, then the order in which the nodes will be visited is ______

The following sequence of operations is performed on stack: PUSH (10),PUSH (20),POP,PUSH (10),PUSH (20),POP,POP,POP,PUSH (20),POP The sequence of the value popped out is:

Find the maximum clock frequency at which the counter in Fig., can be operated. Assume that the propagation delay through each flip-flop and $$AND$$ gate is $$10$$ $$ns.$$ Also assume that the setup time for the $$JK$$ inputs of the flip-flops is negligible.