20. A single-phase transformer is rated at 220/440V, 10kVA. Leakage reactance measured from the low-voltage side is 0.24Ω. Choose a false statement.
(A) Base impedance at the low-voltage side is 4.84Ω
(B) Base impedance at the high-voltage side is 19.36Ω
(C) Leakage reactance at the low-voltage side is 0.050 pu
(D) Leakage reactance at the high-voltage side is 0.012 pu

16. An ideal boost converter is operated in CCM mode. Input voltage is 10V and output voltage is 50V and load resistance is 10Ω. Choose a false statement.(A) Average inductor current 5A(B) Duty ratio is 0.8(C) Input power is 250W(D) Output power is 250W

17. An ideal boost-boost converter is operated in CCM mode. Input voltage is 10V and output voltage is 20V and load resistance is 10Ω. Choose a false statement.(A) Duty ratio is 0.67(B) Average inductor current is 8A(C) Input current is 4A(D) Output current 2A

18. Determine the speed of rotation of a synchronous generator with parameters 480V/50Hz/six poles/delta-connection.(A) 600rpm(B) 1000rpm(C) 1200rpm(D) 2000rpm

19. A four-pole, 60Hz induction motor supplies 15kW to a load at 5% slip. Choose a false statement.(A) Synchronous speed is 1800 rpm(B) Rotor speed is 1710 rpm(C) Rotor frequency is 3Hz(D) Load torque is 41.7N·m

1. Suppose we have a byte-addressable machine, i.e., each byte is accessed via an address. Let the locations for an array be allocated in a row-major manner, and each element of an array takes 4 bytes. Assume that the address of the first byte of the array is 500 in all the following cases. Which of the following is true?(A) The address of the element A10 in an array declared as A100 is 24586；(B) The address of the element A1030] in an array declared as A[100[300] is 177899；(C) The address of the element A[10] in an array declared as A[100] is 536；(D) The address of the element A1030 in an array declared as A100300 is 76457217.

2. Let a, b and c are variables. Which of the following is a postfix expression?(A) a/(b + c)；(B) xabc/+；(C) abc + /；(D) /a + bc.

3. Let a = 3, b = 8, c = 6 and d = 5. What is the value of the prefix expression × ba + dc?(A) 13；(B) 14；(C) 15；(D) 16.

4. The ADT stack can be defined by the following axioms:(aStack.createStack()).isEmpty() = true(aStack.push(item)).isEmpty() = false(aStack.createStack()).pop() = error(aStack.createStack()).getTop() = error(aStack.push(item)).getTop() = item(aStack.push(item)).pop() = aStackFor the following expression:(((((((aStack.createStack()).push(1)).push(2)).pop()).push(3)).pop()).pop()).isEmpty()what is the value returned?(A) an item；(B) a stack；(C) true；(D) false.

5. Suppose a stack is implemented by a variable top and an array B[4]. Note that top denotes the index of the last element pushed. Initially, the stack is empty. Then the following operations are performed in order:push(1), push(2), pop(), push(3), push(4), pop(), getTop(), push(5), pop(), push(6).Which of the following is true in the end?(A) B[0] = 3；(B) B contains 4 integers available；(C) An overflow occurred, so the operations could not be completely done；(D) top is 2.

6. Let the height of a tree be the number of nodes along the longest path from the root node to the leaf nodes. Consider the integers 30, 41, 25, 29, 94, 37, 70, 23, 65, 75, 68, 67 in order to create a binary search tree. Which of the following is true?(A) The node for 37 is a leaf node；(B) The root node is 41；(C) The node for 70 has only one child；(D) The height of the tree is 5.