Class XI Computer Science Chapter 1 MCQs (Mixed) — Answers & Explanations
Chapter 1 in Class XI Computer Science usually starts with the computer system basics: how CPU and memory work together, what input/output devices do, and why software (OS, compilers, utilities) matters. These topics feel simple, but MCQs often test small definitions like “volatile vs non-volatile”, “compiler vs interpreter”, and “system vs application software”.
This page gives a mixed set of exam-style MCQs with clear explanations. If you prefer step-by-step practice (Easy → Medium → Hard), use the difficulty-wise page linked at the end.
MCQs (Mixed Practice)
1) Which part of CPU performs arithmetic and logical operations?
A. Control Unit (CU)
B. Arithmetic Logic Unit (ALU)
C. Register
D. Cache
Correct Answer: B
Explanation: ALU does calculations and logical comparisons.
2) RAM is called volatile memory because
A. it cannot be written
B. it is slower than ROM
C. data is lost when power is off
D. it stores data permanently
Correct Answer: C
3) Which memory is typically the fastest?
A. Cache memory
B. Hard disk
C. DVD
D. Pen drive
Correct Answer: A
Explanation: Cache is designed for very fast CPU access.
4) Which of the following is an example of system software?
A. Spreadsheet application
B. Web browser
C. Operating system
D. Photo editor
Correct Answer: C
5) A compiler is used to
A. translate entire source code to machine code
B. execute code line by line
C. permanently store files
D. format hard disk
Correct Answer: A
Explanation: An interpreter executes line by line; a compiler translates the full program.
Revision Tip: Don’t mix up “compiler vs interpreter” — exam MCQs love this difference.
6) Which device is an output device?
A. Scanner
B. Microphone
C. Monitor
D. Joystick
Correct Answer: C
7) ROM is non-volatile. That means
A. it loses data without power
B. it retains data without power
C. it is used only for temporary storage
D. it cannot store instructions
Correct Answer: B
8) The primary role of an operating system is to
A. compile programs
B. manage computer resources
C. design web pages
D. increase monitor resolution
Correct Answer: B
9) Which is an example of secondary storage?
A. Cache
B. Registers
C. Hard disk / SSD
D. RAM
Correct Answer: C
10) Which interface uses typed commands to interact with a computer?
A. GUI
B. CLI
C. Gesture UI
D. Touch UI
Correct Answer: B
Explanation: Command Line Interface uses typed commands.
11) Which is a correct statement about FOSS?
A. Source code is always hidden
B. Users can study and modify source code
C. It can never be shared
D. It is always paid
Correct Answer: B
12) A debugger is used to
A. store files
B. find and fix errors in programs
C. print documents
D. increase RAM
Correct Answer: B
13) Which unit is used to measure CPU clock speed?
A. Hertz (Hz)
B. Bytes
C. Inches
D. Pixels
Correct Answer: A
14) Which bus carries memory addresses?
A. Data bus
B. Address bus
C. Control bus
D. USB
Correct Answer: B
15) “KB, MB, GB” are units of
A. processing speed
B. storage capacity
C. screen size
D. network latency
Correct Answer: B
Next: Practice Level-Wise
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