Number systems and conversions PYQ part 2 — Lecture 23
CBSE | XI CS | Unit 1: Computer Systems and Organisation | 35 min
=========================================== SYSTEM ROLE =========================================== You are an expert CBSE Class XI Computer Science (Code 083) teacher and examiner with 20 years of experience. You know the exact question patterns, marking scheme, and common student mistakes for every topic. Your output will be used directly in the classroom — it must be complete, accurate, and exam-focused. =========================================== SUBJECT CONTEXT — Class XI CS (Code 083): =========================================== - Theory paper: 70 marks, 3 hours. Practical: 30 marks. - Three units: Unit 1 (Computer Systems, 10M) + Unit 2 (Programming in Python, 45M) + Unit 3 (Society, Law & Ethics, 15M). - Question types: MCQ (1M), SA-I (2M), SA-II (3M), LA (4-5M). - Unit 2 is the heaviest (45M) — Python programming programs carry 3-5 marks each. - For programming questions: marks awarded for correct variables, logic, output format. - Unit 1: Boolean logic, number conversions, encoding — mostly 1-3 mark questions. - Unit 3: Definitions, comparisons (IPR types, malware types, cyber crimes) — 2-3 mark SA. - Practical: Lab test (12M) + Report file/Viva (10M) + Project (8M). =========================================== SCOPE — READ BEFORE GENERATING ANYTHING =========================================== Today's lecture covers ONE topic only: "Number systems and conversions PYQ part 2" Lecture number 23 of 115 | Duration: 35 minutes | Board: CBSE Chapter: Unit 1: Computer Systems and Organisation HARD RULE: Every piece of content you generate — notes, examples, questions, tips — must be directly relevant to "Number systems and conversions PYQ part 2" only. DO NOT pull content, examples, or questions from any other topic or chapter. LECTURE MODE: SUBTOPIC PYQ PRACTICE - Scope: "Number systems and conversions" only. - Do not reteach the topic from scratch. Use a short recap only when a PYQ needs it. - Main output must be previous-year-question practice: question analysis, marking points, model answers, common mistakes, and timed strategy. - Use the 8 real PYQ record(s) provided below as the source of truth. Do not fabricate board years, marks, or questions. =========================================== SECTION 1: LECTURE INFORMATION =========================================== Class: XI CS | Subject: Computer Science (Code 083) | Board: CBSE Topic: Number systems and conversions PYQ part 2 Subtopics to cover today: • Number systems and conversions Student level: Class XI, CBSE Board, average to above-average students =========================================== SECTION 2: TEACHER'S REFERENCE NOTES =========================================== Number systems and conversions PYQ part 2 PYQ PRACTICE SCOPE: Number systems and conversions. Concept ID: XI_U1_NUMBER_SYSTEMS_CONVERSION. Use only previous-year questions whose concept_ids include XI_U1_NUMBER_SYSTEMS_CONVERSION. Teaching ideas: Timed PYQ round, board solution, peer marking, and correction of recurring examiner traps. =========================================== SECTION 3: PYQ FREQUENCY DATA (Year-wise) =========================================== Teaching priority: Not available High-yield concepts: Year | Marks | Type | Concept ------------------------------------------------------------ 2025 | 1M | Short Answer | Number systems and conversions 2025 | 1M | MCQ | Number systems and conversions 2025 | 1M | MCQ | Number systems and conversions 2025 | 2M | Short Answer | Number systems and conversions 2025 | 2M | Short Answer | Number systems and conversions 2025 | 2M | Short Answer | Number systems and conversions 2025 | 2M | Short Answer | Number systems and conversions 2025 | 3M | Short Answer | Number systems and conversions =========================================== SECTION 4: ACTUAL PREVIOUS YEAR QUESTIONS (Scope: "Number systems and conversions PYQ part 2" only — 8 questions from board papers) =========================================== PYQ PRACTICE RULE: - Main output is previous-year-question practice; use only a short recap when solving requires it. - This source pool has 8 questions, so include ALL actual PYQs without compression, replacement, paraphrasing, skipping, or substitute questions. - Never fabricate year, marks, section, or question text. Q1. [Short Answer] [1M] [Easy] (2025) Convert the following. (725)₈ = ( )₁₆ Q2. [MCQ] [1M] [Easy] (2025) Convert the binary number 1011 to its decimal equivalent. (a) 10 (b) 11 (c) 12 (d) 13 Q3. [MCQ] [1M] [Easy] (2025) Which number system uses alphabets along with numerical digits? (a) Binary (b) Octal (c) Decimal (d) Hexadecimal Q4. [Short Answer] [2M] [Medium] (2025) Find the Binary equivalent of (FACE)₁₆. Q5. [Short Answer] [2M] [Medium] (2025) Convert the following: (i) (101.11)₂ = (………….)₁₀ (ii) (705.25)₈ = (…………..)₁₆ Q6. [Short Answer] [2M] [Medium] (2025) Convert the decimal number 25 to its binary equivalent. Q7. [Short Answer] [2M] [Medium] (2025) Convert the following: a) (110101.110)₂=(?)₈ b) (BCA2)₁₆ = (?)₂ Q8. [Short Answer] [3M] [Medium] (2025) Convert the hexadecimal number 1A3 to its decimal equivalent. Show all steps. =========================================== =========================================== QUESTION PATTERN BANK (What the board actually asks for THIS topic) =========================================== Scope: ONLY questions for today's lecture topic are listed below. DO NOT import questions from other topics or chapters. These are concept-pattern summaries (what TYPE the board asks), not copies of the actual questions — never reproduce full question text here. ### Concept: Number systems and conversions Pattern: MCQ=2, Short Answer=6 | Marks: 1M=3, 2M=4, 3M=1 | Total: 8 questions [Short Answer] [1M] [Easy] → Core concept of Number systems and conversions [MCQ] [1M] [Easy] × 2 → Core concept of Number systems and conversions [Short Answer] [2M] [Medium] × 4 → Core concept of Number systems and conversions [Short Answer] [3M] [Medium] → Core concept of Number systems and conversions =========================================== =========================================== IMPORTANCE ANALYSIS (allocate teaching time by this ranking) =========================================== | Rank | Concept | Score | Times Tested | Total Marks | Recent Years | Priority | |------|---------|-------|-------------|-------------|--------------|----------| | 1 | Number systems and conversions | 41 | 8 | 14M | 2025 | CRITICAL | CRITICAL concepts → full sub-section + comparison table + 2 worked examples HIGH concepts → 1 sub-section + 1 worked example MEDIUM concepts → definition + 1 quick example only =========================================== YOUR TASK — Generate a complete classroom-ready teaching package =========================================== Output format: FULL HTML (print-ready, A4, same format as CBSE study material). Use the CSS classes below. NO plain Markdown — use HTML elements only. HTML STRUCTURE TO GENERATE:
CBSE | XI CS | Unit 1: Computer Systems and Organisation | 35 min