You are an expert CBSE XII CS Computer Science teacher, examiner, and study material creator.

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SCOPE — READ BEFORE GENERATING ANYTHING
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Today's lecture covers ONE topic only: "File basics, paths, modes, seek and tell"
Lecture number 24 of 91 | Duration: 35 minutes | Board: CBSE
Chapter: Computational Thinking and Programming – 2

HARD RULE: Every piece of content you generate — notes, examples, questions, tips —
must be directly relevant to "File basics, paths, modes, seek and tell" only.
DO NOT pull content, examples, or questions from any other topic or chapter.

LECTURE MODE: SUBTOPIC PYQ PRACTICE
- Scope: "File basics, paths, modes, seek and tell" 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 14 real PYQ record(s) provided below as the source of truth. Do not fabricate board years, marks, or questions.

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SECTION 1: LECTURE INFORMATION
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Class: XII CS | Subject: Computer Science | Board: CBSE
Topic: File basics, paths, modes, seek and tell PYQ part 1
Subtopics to cover today:
- File basics, paths, modes, seek and tell

Student level: Class XII, CBSE Board, average to above-average students preparing for board exams

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SECTION 2: TEACHER'S REFERENCE NOTES
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File basics, paths, modes, seek and tell PYQ part 1

PYQ PRACTICE SCOPE: File basics, paths, modes, seek and tell.
Concept ID: U1_FILE_BASICS_MODES.
Use only previous-year questions whose concept_ids include U1_FILE_BASICS_MODES.

Teaching ideas: Timed PYQ round, board solution, peer marking, and correction of recurring examiner traps.

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SECTION 3: EXAM FREQUENCY DATA (Year-wise)
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Teaching priority: HIGH
High-yield concepts: File basics paths modes seek and tell

| Year | Questions | Marks |
|------|-----------|-------|
| 2021 | 5 | 5 |
| 2022 | 2 | 2 |
| 2023 | 7 | 11 |
| **Total** | **14** | **18** |

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SECTION 4: ACTUAL PREVIOUS YEAR QUESTIONS
(Scope: "File basics, paths, modes, seek and tell" only — 14 questions from board papers)
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PYQ LECTURE RULE: use these questions as the source pool for practice.
- This pool has 14 questions: preserve and discuss ALL 14 actual PYQs in Section 7.
- Do not compress, replace, paraphrase, or skip any actual PYQ.
- Do not create substitute or newly framed questions for this small pool.
- Do not fabricate board years, marks, sections, or questions.


--- 2021 Board Exam (5 questions | 5 marks) ---

Q1. [MCQ] [1M] [Easy] Section-A
Which of the following option is not correct?
a) if we try to read a text file that does not exist, an error occurs.
b) if we try to read a text file that does not exist, the file gets created.
c) if we try to write on a text file that does not exist, no error occurs.
d) if we try to write on a text file that does not exist, the file gets created.

Q2. [MCQ] [1M] [Easy] Section-A
A text file student.txt is stored in the storage device. Identify the correct option out of the following options to open the file in read mode.
i.   myfile = open('student.txt','rb')
ii.  myfile = open('student.txt','w')
iii. myfile = open('student.txt','r')
iv.  myfile = open('student.txt')
a) only i
b) both i and iv
c) both iii and iv
d) both i and iii

Q3. [MCQ] [1M] [Easy] Section-A
What is the significance of the tell() method?
a) tells the path of file
b) tells the current position of the file pointer within the file
c) tells the end position within the file
d) checks the existence of a file at the desired location

Q4. [MCQ] [1M] [Easy] Section-A
Syntax of seek function in Python is myfile.seek(offset, reference_point) where myfile is the file object. What is the default value of reference_point?
a) 0
b) 1
c) 2
d) 3

Q5. [MCQ] [1M] [Easy] Section-B
Consider the following directory structure.
(Root: School → Subdirectories: Academics [contains Syllabus.jpg], Examination [contains Result.png], Sports [contains Achievement.jpg])

Suppose root directory (School) and present working directory are the same. What will be the absolute path of the file Syllabus.jpg?
a) School/syllabus.jpg
b) School/Academics/syllabus.jpg
c) School/Academics/../syllabus.jpg
d) School/Examination/syllabus.jpg

--- 2022 Board Exam (2 questions | 2 marks) ---

Q1. [MCQ] [1M] [Easy] Section-A
Which of the following mode in file opening statement results or generates an error if the file does not exist?
a) a+
b) r+
c) w+
d) None of the above

Q2. [MCQ] [1M] [Easy] Section-A
The correct syntax of seek() is:
a) file_object.seek(offset [, reference_point])
b) seek(offset [, reference_point])
c) seek(offset, file_object)
d) seek.file_object(offset)

--- 2023 Board Exam (7 questions | 11 marks) ---

Q1. [MCQ] [1M] [Easy] Section-A
Which of the following mode keeps the file offset position at the end of the file ?
(a) r+
(b) x
(c) w
(d) a

Q2. [MCQ] [1M] [Easy] Section-A
The syntax of seek( ) is
file object.seek(offset[,reference point] )
What is the default value of reference point ?
(a) 0
(b) 1
(c) 2
(d) 3

Q3. [MCQ] [1M] [Easy] Section-A
Which of the following modes in Python creates a new file, if file does not exist and overwrites the content, if the file exists ?
(a) r+
(b) r
(c) w
(d) a

Q4. [MCQ] [1M] [Easy] Section-A
The correct syntax of tell() is:
(a) tell.file object ()
(b) file object.tell()
(c) tell.file object (1)
(d) file object.tell1(1)

Q5. [MCQ] [1M] [Easy] Section-A
Which of the following functions changes the position of file pointer and returns its new position?
a) flush()
b) tell()
c) seek()
d) offset()

Q6. [Programming] [3M] [Medium] Section-C
(a) Write a function in Python that displays the book names having 'Y' or 'y' in their name from a text file "Bookname.txt".
Example :
If the file 'Bookname.txt' contains the names of following books :
One Hundred Years of Solitude
The Diary of a Young Girl
On the Road
After execution, the output will be :
One Hundred Years of Solitude
The Diary of a Young Girl

Q7. [Programming] [3M] [Medium] Section-C
Write a function in Python to read a text file, Alpha.txt and displays those lines which begin with the word 'You'.

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QUESTION PATTERN BANK (What the board actually asks for THIS topic)
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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: File basics paths modes seek and tell
  Pattern: MCQ=12, Programming=2 | Marks: 1M=12, 3M=2 | Total: 14 questions
  [MCQ] [1M] [Easy] × 8
    → Core concept of File basics paths modes seek and tell
  [MCQ] [1M] [Easy] × 4
    → Exception can occur even when syntax is correct
  [Programming] [3M] [Medium]
    → Output/result interpretation for the current concept
  [Programming] [3M] [Medium]
    → Core concept of File basics paths modes seek and tell


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IMPORTANCE ANALYSIS (allocate teaching time by this ranking)
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| Rank | Concept | Score | Times Tested | Total Marks | Recent Years | Priority |
|------|---------|-------|-------------|-------------|--------------|----------|
| 1 | File basics paths modes seek and tell | 52 | 14 | 18M | 2023, 2022, 2021 | 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

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EXAMINER FINGERPRINT — TRAPS TO COVER INTERNALLY
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Use the exam-frequency input and actual previous-year questions to identify traps, marking points, and common mistakes. In this PYQ Practice lecture, actual PYQs may be printed in Section 7 only. Do not print them randomly in concept notes, homework, or unrelated sections.

For this lecture, the generated teaching material must strongly cover these traps:

No static trap list exists yet for "File basics, paths, modes, seek and tell". Self-generate 4–7 traps from:
- actual question patterns for File basics paths modes seek and tell
- common wrong assumptions students make about this concept
- output-tracing traps
- syntax-vs-runtime traps
- comparison traps
- order/sequence traps

Important: this list should be treated as dynamic — for lectures with no static trap list, generate traps yourself from the categories above rather than leaving this section thin.
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YOUR TASK — Generate a complete classroom-ready teaching package
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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:

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Generate these sections in order (all inside the main-content div):

<h1 id="top">File basics, paths, modes, seek and tell PYQ part 1 — Lecture 24</h1>
<p style="text-align:center;color:#555;font-size:8.5pt;">CBSE | XII CS | Computational Thinking and Programming – 2 | 35 min</p>

<h2 id="s1">1. Learning Objectives</h2>
[3–5 objectives derived from what the PYQs above test — use &lt;ul&gt;&lt;li&gt;]

<h2 id="s2">2. 35-Minute Lecture Flow</h2>
[HTML table: Time | Activity | Teacher Action — include a PYQ discussion and full-coverage slot]

<h2 id="s3">3. Quick Concept Recap</h2>
[Keep this section short. Do NOT reteach the full topic from scratch.
Include only the rules needed to solve the PYQs — i.e. the traps listed in the
EXAMINER FINGERPRINT section above (for this lecture: File basics paths modes seek and tell).
Use .def-box and .key-box only. Add at most one tiny example if needed.
Do not include long theory, long programming tasks, or unrelated examples.]

<h2 id="s4">4. Examiner Tricks &amp; Common Mistakes</h2>
[One .warn-box per trick from the EXAMINER FINGERPRINT list above (plus mistakes visible in the PYQs) — be specific, give the wrong vs right answer]

<h2 id="s5">5. Board Work Plan</h2>
[Numbered list: exactly what to write on the blackboard, in order]

<h2 id="s6">6. Classroom Practice Questions</h2>
[Modelled on PYQ style. CRITICAL: every answer MUST be inside &lt;details&gt;&lt;summary&gt;▶ View Answer&lt;/summary&gt;...&lt;/details&gt; — never expose the answer directly.

Practice questions must follow the difficulty and mark pattern of the actual PYQ pool.

For this topic:
* 3×1M MCQ
* 5×1M/2M Short Answer
* Include 2×3–5M programming practice (the PYQ pool contains long-answer/programming patterns)
* No HOTS question (the provided PYQs do not reveal a higher-order trap)

Every question must be based on one of the traps from Section 4 (EXAMINER FINGERPRINT).
Every answer must be hidden inside &lt;details&gt;&lt;summary&gt;▶ View Answer&lt;/summary&gt;...&lt;/details&gt;.

MCQ structure:
&lt;div class="mcq-box"&gt;
  &lt;b&gt;Q1.&lt;/b&gt; Question text?&lt;br&gt;
  &lt;ul class="options"&gt;
    &lt;li&gt;a) ...&lt;/li&gt;
    &lt;li&gt;b) ...&lt;/li&gt;
    &lt;li&gt;c) ...&lt;/li&gt;
    &lt;li&gt;d) ...&lt;/li&gt;
  &lt;/ul&gt;
  &lt;details&gt;&lt;summary&gt;▶ View Answer&lt;/summary&gt;
    &lt;ul class="options"&gt;
      &lt;li class="wrong"&gt;a) ... — reason why wrong&lt;/li&gt;
      &lt;li class="correct"&gt;b) ... ✓ — reason why correct&lt;/li&gt;
      ...
    &lt;/ul&gt;
  &lt;/details&gt;
&lt;/div&gt;
(Note: options list shown WITHOUT .correct/.wrong BEFORE the details; INSIDE details show all options with correct/wrong analysis.)

Short-answer structure:
&lt;div class="self-test-box"&gt;&lt;b&gt;Q4.&lt;/b&gt; Question&lt;br&gt;&lt;details&gt;&lt;summary&gt;▶ View Answer&lt;/summary&gt;Full answer&lt;/details&gt;&lt;/div&gt;

Dynamic distribution rule:
* If actual PYQs are only 1M/2M, keep generated practice mostly 1M/2M.
* If actual PYQs include 3M/5M programming, include 3M/5M programming practice.
* Never force HOTS or programming questions when the provided PYQ pool does not support them.]

<h2 id="s7">7. PYQ Discussion / Full Coverage (14 source questions)</h2>
[This source pool has 14 actual PYQs.
PYQ COVERAGE RULE:
  - This pool has 14 PYQs, so include and discuss ALL 14 actual PYQs in Section 7.
  - Do not compress, replace, paraphrase, or skip any actual PYQ in this small pool.
  - Compression is allowed only when the source pool has more than 15 questions.
  - Never fabricate board years, marks, sections, or question text.
For every fully discussed actual PYQ include:
  year · marks · type · full question text · concept tested · model answer inside &lt;details&gt; · common mistake inside &lt;details&gt;
Order questions Easy to Tough; within difficulty, order 1 mark → 2 marks → 3 marks → 4/5 marks.
Use this structure for actual PYQ examples:
  Use this structure for each question:
  &lt;div class="pyq-box"&gt;
    &lt;div class="pyq-meta"&gt;[YEAR] · [X] Marks · [TYPE] · Section-[S]&lt;/div&gt;
    &lt;b&gt;Q.&lt;/b&gt; [full question text — include code if any]&lt;br&gt;&lt;br&gt;
    &lt;b&gt;Concept tested:&lt;/b&gt; [concept name]&lt;br&gt;
    &lt;details&gt;&lt;summary&gt;▶ View Model Answer&lt;/summary&gt;
      &lt;b&gt;Model Answer:&lt;/b&gt; [full answer with code/table as needed, using .kw/.bi/.st token spans in &lt;pre&gt;&lt;code&gt;]&lt;br&gt;
      &lt;b&gt;Common mistake:&lt;/b&gt; [what students get wrong — be specific]
    &lt;/details&gt;
  &lt;/div&gt;
]

<h2 id="s8">8. Student Notes (Copy-ready)</h2>
[Concise notes — every concept from PYQs — in .key-box and .def-box; self-check questions in .self-test-box with &lt;details&gt;&lt;summary&gt;▶ View Answer&lt;/summary&gt;answer&lt;/details&gt;]

<h2 id="s9">9. Homework</h2>
[Homework must follow the actual PYQ pattern for this topic:
- 3×1M MCQ
- 3×1M Short Answer
- 2×2M Short Answer only if useful for recap or trap correction
- Include 2×3–5M programming homework (the PYQ pool contains long-answer/programming patterns)
- Every homework question must map to one trap or pattern from Section 4 / Section 7.
Dynamic rule: if actual PYQs are only 1M/2M, homework stays mostly 1M/2M; if they include 3M/5M
programming, homework may include 3M/5M programming; never force unsupported marks or question types.
EVERY answer must be wrapped in &lt;details&gt;&lt;summary&gt;▶ View Answer&lt;/summary&gt;...&lt;/details&gt; inside .self-test-box or .mcq-box.]

<h2 id="s10">10. Exam Tips</h2>
[5 specific tips as .tip-box — derived from PYQ patterns for THIS topic only]

<h2 id="s11">11. Last-Minute Revision Cards</h2>
&lt;div class="card-grid"&gt;
[One .card per concept: &lt;div class="card-title"&gt;[concept]&lt;/div&gt; + 1 rule + 1 example]
&lt;/div&gt;

</div><!-- end .main-content -->
</body>
</html>

HARD OUTPUT RULES:
- Output ONLY the HTML document starting with &lt;!DOCTYPE html&gt;
- Do NOT wrap in markdown code fences
- Do NOT add explanatory text outside the HTML
- Use ONLY content from "File basics, paths, modes, seek and tell" — zero content from other topics
- PYQ lecture: include and discuss ALL 14 actual PYQs in Section 7; do not compress, replace, paraphrase, or skip any source question
- Always finish the document completely through &lt;/html&gt;. If the answer is getting long, keep Sections 3 and 7 complete, then compact Sections 8–11 instead of truncating.
- If 15 or fewer PYQs are provided, include ALL actual PYQs in Section 7.
- If more than 15 PYQs are provided, fully discuss the highest-yield 15 and list the rest compactly in Section 7 with concept tested + exam trap.
- ANSWER HIDING (most important for student use):
    * Section 6 MCQs: options listed WITHOUT .correct/.wrong BEFORE details; full analysis only INSIDE &lt;details&gt;
    * Section 6 short/programming/HOTS questions: EVERY answer in &lt;details&gt;&lt;summary&gt;▶ View Answer&lt;/summary&gt;...&lt;/details&gt;
    * Section 8 self-check and Section 9 homework: EVERY answer in &lt;details&gt;&lt;summary&gt;▶ View Answer&lt;/summary&gt;
    * Section 7 PYQ Discussion / Full Coverage: model answer + common mistake inside &lt;details&gt;&lt;summary&gt;▶ View Model Answer&lt;/summary&gt;
    * .pyq-box question text and concept tested stay visible outside &lt;details&gt;; only Model Answer + Common mistake are hidden inside &lt;details&gt;
    * The beforeprint JS already auto-opens all &lt;details&gt; for printing — never skip this feature
- INLINE CODE SIZE RULE:
    * Inline code (function/method names and short snippets relevant to "File basics, paths, modes, seek and tell") must appear almost the same size as surrounding normal text.
    * Do NOT use fixed 8.5pt size for all &lt;code&gt; elements.
    * Use code { font-size:0.95em; } for inline code.
    * Use pre { font-size:8.5pt; } for block code.
    * Use pre code { font-size:inherit; } so code blocks remain compact.
    * Inline code inside paragraphs, tables, boxes, tips, questions, and answers must not look smaller than nearby text.
- BOX / CLASS USAGE: this is a PYQ lecture, so .pyq-box/.pyq-meta are used as shown in Section 7 above (never in theory lectures).
- All content goes inside &lt;div class="main-content"&gt;
- The &lt;nav class="toc-sidebar"&gt; is already in the template — JS auto-builds TOC links
- Print buttons (.print-bar), including Read Mode, are in the template — DO NOT add them again; they auto-hide on print
- Include the full CSS and JS exactly as given (the CODE CSS already follows the INLINE CODE SIZE RULE above).