Q1. What is the decimal equivalent of the binary number 1101?
The binary number 1101 equals 1×8 + 1×4 + 0×2 + 1×1 = 13 in decimal.
Class 9 Computer Chapter 3: Digital Systems and Logic Design MCQs With Explanations
Practice Class 9 Computer Chapter 3: Digital Systems and Logic Design MCQs with explanations for Pakistani board exams. Includes solved objective questions, answer checking, chapter revision guidance and next chapter suggestions.
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Chapter 3: Digital Systems and Logic Design Objective Preparation
Use this page for direct chapter practice, answer checking and explanation review. It is available through the clean URL shown in the browser, so students can bookmark and share this exact chapter.
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4Topics represented
Topics found: Number System, Combinational Circuits, Logic Gates, Boolean Algebra
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Digital Systems and Logic Design MCQs With Explanations
Q2. In a half-adder circuit, the carry is generated by which operation?
The carry output of a half-adder is produced only when both input bits are 1, which is the logical AND operation. XOR generates the sum, not the carry.
Q3. Which logic gate outputs true only if both inputs are true?
An AND gate produces a true output exclusively when all its inputs are true, matching the definition given.
Q4. What is the dual of the Boolean expression A⋅0=0?
The dual of a Boolean expression is found by swapping AND (⋅) with OR (+) and 0 with 1, making the dual of A⋅0=0 equal to A+1=1.
Q5. Which of the following Boolean expressions represents the OR operation?
The OR operation in Boolean algebra is standardly denoted by the plus sign A+B, which outputs true when at least one input is true.
Chapter 3: Digital Systems and Logic Design Revision Guide
Complete the MCQs first, then review every incorrect answer against the textbook heading where that concept appears. For biology and other science subjects, pay attention to terminology, diagrams, sequence of processes, examples and differences between similar structures or functions.
This chapter page keeps the exact class, subject, chapter, question count, answer checking, explanations and follow-up chapters together, so students can revise from one focused URL instead of searching through the full book again.
Class 9 Computer Science MCQ Preparation: Digital Systems and Logic Design
This page supports Matric Part 1 practice in Computer Science. At this stage, the main purpose is building the definitions, symbols, rules and study habits needed for later matric work. The questions available here should be used with the current textbook and the instructions issued by the learner's school or examination board.
What Computer Science MCQs can test
In Computer Science, objective questions commonly draw on hardware and software concepts, data representation, networks, algorithms, programming syntax, logic, databases and digital responsibility. A useful answer is based on the exact wording and concept, not simply on recognising a familiar option. For this subject, learners should trace instructions in order, distinguish related technical terms and test small code or logic examples step by step.
Digital Systems and Logic Design: what to focus on
Technical vocabulary, system roles, ordered procedures, data handling, logic and the output of instructions.
Trace the process one step at a time and write how the input, stored value or output changes at each stage.
Common mistakes for Class 9 learners
In this subject, frequent errors include confusing hardware with software roles, ignoring syntax, skipping an algorithm step or predicting output without tracing variable changes. Separate new terms that look similar and connect every formula, rule or definition with at least one textbook example. When the page marks an answer as incorrect, the next step should be to identify the mistaken idea and verify it, rather than memorising the displayed answer letter.
A practical revision routine
Read a small textbook section, answer a focused set of MCQs and correct the underlying idea before starting the next section. Before attempting the MCQs, review technical definitions, comparisons, diagrams, algorithm stages, code traces, database terms and practical examples. Complete a manageable set without notes, check the result, and divide errors into missing knowledge, misunderstood concepts and careless reading. Revise the appropriate section before repeating the chapter.
How to review Digital Systems and Logic Design after the quiz
List the questions you missed from Digital Systems and Logic Design and write the textbook heading connected with each one. Explain the correct idea in your own words, then return later and answer a fresh set. This gives the chapter page a clear purpose: finding specific weaknesses in Computer Science rather than only collecting a score.
Accuracy and responsible use
Explanations are provided where they exist in the question bank, but educational databases can contain incomplete or mistaken material. Confirm disputed answers with an authoritative textbook or teacher. Ahmad Learning Hub provides a practice resource and does not claim that a question will appear in an examination or that every available item represents an official board question.