Logic Gate MCQ

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Logic Gate MCQ

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Multiple Choice Questions

Q.1. What logic function is produced by adding inverters to the inputs of an OR gate?

  • NOR
  • NAND
  • AND
  • X-NOR

Answer: NAND

Q.2. What logic function is produced by adding an inverter to each input and output of an AND gate?

  • NOR
  • NAND
  • X-OR
  • OR

Answer: OR

Q.3. What logic function is produced by adding an inverter to each input and output of an OR gate?

  • NAND
  • NOR
  • AND
  • X-OR

Answer: AND

Q.4. Which of the following gates is known as a coincidence detector?

  • AND gate
  • NAND gate
  • X-OR
  • X-NOR gate  

Answer: X-NOR gate

Q.5. Which of the following gates is known as anticoincidence detector?

  • OR gate  
  • X-OR gate
  • AND gate
  • X-NOR gate

Answer: X-OR gate

Q.6. The output of a NOR gate is high

  • only when all the inputs are low
  • only when all the inputs are high
  • only when at least one input is high
  • only when at least one input is low

Answer: only when all the inputs are low

Q.7. The output of a NAND gate is low

  • only when all the inputs are low
  • only when all the inputs are high
  • only when at least one input is high
  • only when at least one input is low

Answer: only when all the inputs are high

Q.8. How many NOR gates are required to obtain AND operation?

  • 2
  • 3
  • 4
  • 1

Answer: 3

Q.9. What is the minimum number of NAND gates required to realize an X-OR gate?

  • 3
  • 4
  • 5
  • 6

Answer: 4

Q.10. What is the minimum number of NOR gates required to realize an X-OR gate?

  • 3
  • 4
  • 5
  • 6

Answer: 5

Q.11. An AND gate can be imagined as

  • switches connected in series
  • switches connected in parallel
  • transistors connected in series
  • transistors connected in parallel

Answer: switches connected in series

Q.12. An OR gate can be imagined as

  • switches connected in series
  • switches connected in parallel
  • transistors connected in series
  • transistors connected in parallel

Answer: switches connected in parallel

Q.13. An all or nothing gate is the other name of

  • AND gate
  • OR gate
  • X-OR gate
  • X-NOR gate

Answer: AND gate

Q.14. An any or all gate is the other name of

  • AND gate
  • OR gate
  • X-OR gate
  • X-NOR gate

Answer: OR gate

Q.15. A bubbled AND gate is equivalent to a

  • OR gate
  • NAND gate
  • NOR gate
  • X-OR gate

Answer: NOR gate

Q.16. A bubbled OR gate is equivalent to a

  • AND gate
  • NAND gate
  • NOR gate
  • X-OR gate

Answer: NAND gate

Q.17. A bubbled NAND gate is equivalent to

  • OR gate
  • NAND gate
  • NOR gate
  • X-OR gate

Answer: OR gate

Q.18. A bubbled NOR gate is equivalent to a

  • AND gate
  • NAND gate
  • NOR gate
  • X-OR gate

Answer: AND gate

Q.19. The output of a gate is LOW when at least one of its inputs is HIGH. This is true for

  • AND
  • NAND
  • NOR
  • OR

Answer: NOR

Q.20. The output of a gate is HIGH when at least one of its inputs is LOW. It is true for

  • X-OR
  • NAND
  • NOR
  • OR

Answer: NAND

Q.21. The output of a gate is LOW if and only if all its inputs are HIGH. It is true for

  • AND
  • X-NOR
  • NOR
  • NAND

Answer: NAND

Q.22. The output of a gate is HIGH if and only if all its inputs are LOW. It is true for

  • NOR
  • X-OR
  • NAND
  • X-NOR

Answer: NOR

Q.23. The most suitable gate for comparing two bits is

  • AND
  • OR
  • NAND
  • X-OR

Answer: X-OR

Q.24. Which of the following gates cannot be used as an inverter?

  • NAND
  • AND
  • NOR
  • X-NOR

Answer: AND

Q.25. A gate is enabled when its enable input is at logic 1. The gate is

  • OR
  • NAND
  • NOR
  • none of these

Answer: NAND

Q.26. A gate is enabled when its enable input is at logic 0. The gate is

  • NOR
  • AND
  • NAND
  • none of these

Answer: NOR

Q.27. A gate is inhibited when its inhibit input is at logic 1. The gate is

  • AND
  • NAND
  • OR
  • none of these

Answer: OR

Q.28. A gate is disabled when its disable input is at logic 0. The gate is

  • AND
  • NOR
  • OR
  • None of these

Answer: AND

Q.29. The output of a logic gate is 1 when all its inputs are at logic 1. The gate is either

  • a NAND or a NOR
  • an AND or an OR
  • an OR or an X-OR  
  • an AND or a NOR

Answer: an AND or an OR

Q.30. The output of a logic gate is 1 when all its inputs are at logic 0. The gate is either

  • a NAND or a NOR 
  • an AND or an X-NOR
  • an OR or a NAND
  • an X-OR or an X-NOR

Answer: a NAND or a NOR

Q.31. The output of a logic gate is 1 when all its inputs are at logic 1. The gate is either

  • an OR or an X-OR
  • a NAND or an X-NOR
  • an AND or a NAND
  • an OR or an X-NOR

Answer: an OR or an X-NOR

Q.32. The output of a logic gate is 1 when all its inputs are at logic 0. The gate is either

  • a NOR or an X-NOR
  • a NAND or an X-OR
  • an OR or an X-NOR
  • an AND or an X-OR

Answer: a NOR or an X-NOR

Q.33. The output of a logic gate is 0 when all its inputs are at logic 1. The gate is either

  • a NAND or an AND
  • a NAND or an X-OR
  • a NOR or an X-NOR
  • a NAND or an X-NOR

Answer: a NAND or an AND

Q.34. The output of a logic gate is 0 when all its inputs are at logic 0. The gate is either

  • an AND or a NOR
  • a NAND or an X-OR
  • an OR or an X-OR
  • an OR or an X-NOR

Answer: an OR or an X-OR

Q.35. The number of rows in the truth table of a 4-input gate is

  • 4
  • 8
  • 12
  • 16

Answer: 16

Q.36. Which of the following statements is true?

  • OR and NOT gates are necessary and sufficient for realization of any logic function.
  • AND and NOT gates are necessary and sufficient for realization of any logic function.
  • NAND gates are not sufficient to realize any logic function.
  • NOR gates are sufficient to realize any logic function.

Answer: NOR gates are sufficient to realize any logic function.

Objective Questions on Logic Gate

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