Multiple Choice Answer:
1: b, 2: b, 3: c, 4: c, 5: a, 6: b

Short Answer: 
1: Swaps the values stored at first and second.

2: 
         50
         /  
        40
       /  \
      35  45
          / \
         41 47
            /
           46

3: 
 a: no rotation - same tree with 2 left child of 5
 b: right,left rotation around 12
 c: right rotation around 25 or 28

4: (two ways to do this - one has linked-lists, or lists witin indices of the array, one just orders within the array).

Shown here is with linked-list:

	Stage 1			Stage 2			Stage 3			Stage 4
0	1470						1072			382,491
1	2381,491,1531								1072,1233,1470,1531
2	1072,382					1233			2381,2478,2484
3	1233			1531,1233		2381,382		3588
4	2484						1470,2478,2484,491
5							1531,3588
6
7				1470,1072,2478
8	3588,2478		2381,382,2484,3588
9				491


Or in the array:

	Stage 1		Stage 2		Stage 3		Stage 4
0	1470		1531		1072		 382
1	2381		1233		1233		 491
2	 491		1470		2381		1072
3	1531		1072		 382		1233
4	1072		2478		1470		1470
5	 382		2381		2478		1531
6	1233		 382		2484		2381
7	2484		2484		 491		2478
8	3588		3588		1531		2484
9	2478		 491		3588		3588


5: 
void ReverseTree(node_t* root) {
   node_t* temp;

   if (root == null) return;

   temp = root->right;
   root->right = root->left;
   root->left = temp;

   ReverseTree(root->left); ReverseTree(root->right);
}

Long Answer:

1a: 7
1b:
int MyAckerman(int m, int n) {
   if (m==0) {
      return n+1;
   } else if (m!=0 && n==0) {
      return MyAckerman(m-1,1);
   } else {
      return MyAckerman(m-1,MyAckerman(m,n-1));
   }
}

2a:
Array shown as comma delimited values
   
s1: 12,28,7,31,2,45,40,30,50,1
s2: 12,28,7,50,2,45,40,30,31,1
s3: 12,28,45,50,2,7,40,30,31,1
s4: 12,50,45,31,2,7,40,30,28,1
s5: 50,31,45,30,2,7,40,12,28,1

2b:
Heap:

       50
      /  \
    31    45
   /  \   / \
 30    2 7  40
 / \  /
12 28 1