4.6.4.1 Logic gates Quiz: AQA Computer Science, Unit 6

The 20 questions

1. What is the output of a two-input AND gate when both inputs are 1?

   • 0
   • Undefined
   • 1
   • -1

2. Which gate outputs 1 only when its inputs differ?

   • XOR
   • NAND
   • AND
   • NOR

3. What is the output of a two-input NAND gate when both inputs are 1?

   • 0
   • 1
   • Undefined
   • -1

4. Which logic gate gives the inverted output of an OR gate?

   • XOR
   • NAND
   • NOT
   • NOR

5. What is the output of an OR gate when inputs are A = 0 and B = 1?

   • -1
   • 1
   • 0
   • Undefined

6. What is the output of a NOT gate when given an input of 0?

   • -1
   • Undefined
   • 0
   • 1

7. Which Boolean expression is equivalent to the output of a two-input NAND gate with inputs A and B?

   • A XOR B
   • A OR B
   • NOT A AND NOT B
   • NOT(A AND B)

8. What is the output of (A AND B) OR C when A = 1, B = 0, C = 1?

   • 0
   • -1
   • Undefined
   • 1

9. A circuit computes Q = NOT(A OR B). Which input combination gives Q = 1?

   • A = 1, B = 1
   • A = 0, B = 0
   • A = 0, B = 1
   • A = 1, B = 0

10. Which of the following is the Boolean expression for a half-adder's sum output?

    • A OR B
    • A XOR B
    • NOT(A AND B)
    • A AND B

11. Which Boolean expression describes the carry output of a half-adder?

    • A AND B
    • A OR B
    • NOT A AND B
    • A XOR B

12. A half-adder has inputs A = 1 and B = 1. What are its sum and carry outputs?

    • Sum 1, carry 0
    • Sum 1, carry 1
    • Sum 0, carry 1
    • Sum 0, carry 0

13. A full-adder adds inputs A, B and a carry-in C. Which expression gives its sum output?

    • A OR B OR C
    • A AND B AND C
    • A XOR B XOR C
    • (A AND B) OR C

14. A full-adder has A = 1, B = 1 and carry-in C = 1. What are its sum and carry-out values?

    • Sum 0, carry-out 1
    • Sum 1, carry-out 1
    • Sum 1, carry-out 0
    • Sum 0, carry-out 0

15. Which logic gate combines intermediate carry signals to produce the carry-out in a full-adder?

    • OR gate
    • NAND gate
    • AND gate
    • XOR gate

16. A truth table has four rows for two inputs. For which gate is the output 1 only in the row where both inputs are 0?

    • NOR
    • AND
    • XOR
    • NAND

17. What component role is an edge-triggered D-type flip-flop primarily used for?

    • Half adder
    • Memory unit
    • Frequency divider
    • Clock signal

18. A circuit's output is given by Q = NOT(A) AND B. Which input values produce Q = 1?

    • A = 1, B = 0
    • A = 0, B = 0
    • A = 0, B = 1
    • A = 1, B = 1

19. What is the output of an XOR gate when both inputs are 1?

    • Undefined
    • -1
    • 1
    • 0

20. What is the output of A XOR B when input A = 1 and input B = 0?

    • 1
    • 0
    • -1
    • Undefined

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