If stack is empty, then after POP

Q. An implementation of queue Q, using two stacks S1 and S2, is given below:

void insert(Q, x)
{
push(S1, x);
}
void delete (Q, x)
{
if (stack -empty (S2)) then
if ( stack - empty(S1)) then
{
print ("Q is empty");
return;
}
else while (! stack - empty(S1))
{
x = pop (S1);
push(S2, x);
}
x = pop(S2);
}

Let n insert and $(m\le n)$ delete operations be performed in an arbitary order on an empty queue Q. Let x and y be the number of push and pop operations performed respectively in the processes. Which one of the following is true for all m and n?

Q. The five items A, B, C, D and E are pushed in a stack one after the other starting from A. The stack is popped 4 times and each element is inserted in a queue then 2 element are deleted form the queue and pushed back on the stack. Now 1 item is popped from the stack the popped item is _________.

Q. Nature of magnetic force is

Q. The following postfix expression is evaluated using stack:
$\text{6 2 3 * / 3 4 * + 3 2 *}-$
What is top of the stack after third * operations?