271. Which of the following is known as half-adder?
     

1. 1. XOR gate
      

   
   
   

   2. XNOR gate
      

   
   
   

   3. NAND gate
      

   
   
   

   4. NOR gate
      

   
   
   

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1. View Hint View Answer Discuss in Forum

   XOR gate is known as half adder.

   Correct Option: A

   XOR gate is known as half adder.

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272. Expression for Y (A, B, C) in figure, where A, B and C are Boolean variables is—
     
     
     

1. 1. AB + AB

   
   
   

   2. A+ BC

   
   
   

   3. AB + AC

   
   
   

   4. (AB + AB)

   
   
   

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1. View Hint View Answer Discuss in Forum

   The given circuit
   From above circuit, we get
   Y = A B. 1 + AB.C + A B.0 + AB. 0
   or
   Y = A B + ABC
   or
   Y = A (B + BC) = A (B+C) = AB + AC

   
   

   Correct Option: C

   The given circuit
   From above circuit, we get
   Y = A B. 1 + AB.C + A B.0 + AB. 0
   or
   Y = A B + ABC
   or
   Y = A (B + BC) = A (B+C) = AB + AC

   
   

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273. The logic network shown below is—
     
     
     
     

1. 1. Half adder
      

   
   
   

   2. Half subtractor
      

   
   
   

   3. Full adder
      

   
   
   

   4. Full subtractor
      

   
   
   

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   The logic circuit shown above is full adder.
   

   
   

   Correct Option: C

   The logic circuit shown above is full adder.
   

   
   

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274. A full adder can be realized by using—
     

1. 1. One half-adder, two OR gates
      

   
   
   

   2. Two half-adders, one OR gate
      

   
   
   

   3. Two half adders, two OR gates
      

   
   
   

   4. None of these
      

   
   
   

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1. View Hint View Answer Discuss in Forum

   A full adder can be realized by using two half-adders and one OR gate.

   Correct Option: B

   A full adder can be realized by using two half-adders and one OR gate.

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275. How many inputs and outputs does a full subtractor circuit have—
     

1. 1. Two inputs, one output
      

   
   
   

   2. Two inputs, two outputs
      

   
   
   

   3. Two inputs, three outputs
      

   
   
   

   4. Three inputs, two outputs
      

   
   
   

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1. View Hint View Answer Discuss in Forum

   A full-subtractor three inputs and two outputs.

   Correct Option: D

   A full-subtractor three inputs and two outputs.

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