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RRB MCQs

Practice questions are arranged in pages of up to 100 MCQs.

Question 1
Digital ElectronicsLogic Gates

Which logic gate gives a HIGH output only when all its inputs are HIGH?

  • AOR gate
  • BNAND gate
  • CAND gate
  • DXOR gate
Report an error
Correct Answer: C. AND gate
Explanation: An AND gate produces logic HIGH only when all of its inputs are HIGH.
Reference: Standard digital electronics principle
Question 2
Digital ElectronicsNumber Systems

What is the binary equivalent of decimal number 10?

  • A1001
  • B1010
  • C1100
  • D1110
Report an error
Correct Answer: B. 1010
Explanation: Decimal 10 equals 8 + 2, which is 1010 in binary.
Reference: Binary number system fundamentals
Question 3
Network TheoryCircuit Laws

Kirchhoff’s Current Law is based on conservation of?

  • AEnergy
  • BCharge
  • CPower
  • DMomentum
Report an error
Correct Answer: B. Charge
Explanation: KCL follows conservation of electric charge: the algebraic sum of currents at a node is zero.
Reference: Kirchhoff's circuit laws
Question 4
Microprocessors & Microcontrollers8085 Microprocessor

The 8085 microprocessor has an address bus of how many bits?

  • A8 bits
  • B12 bits
  • C16 bits
  • D32 bits
Report an error
Correct Answer: C. 16 bits
Explanation: The 8085 has a 16-bit address bus, allowing it to address 2^16 or 64 KB of memory locations.
Reference: 8085 architecture
Question 5
Measurements & InstrumentationElectronic Instruments

Which instrument is primarily used to display an electrical waveform versus time?

  • AAmmeter
  • BOscilloscope
  • CWattmeter
  • DMegger
Report an error
Correct Answer: B. Oscilloscope
Explanation: An oscilloscope displays voltage waveforms and commonly shows their variation with time.
Reference: Electronic measurement fundamentals