NCERT Classes – Private Learning Platform for Class 6 to 12: RBSE Class 11 Computer Science Answer Key 2026 | कक्षा 11 कंप्यूटर विज्ञान उत्तर कुंजी 2026

🔗 संबंधित लिंक – RBSE Class 11 Computer Science 2026

RBSE Class 11 Computer Science Answer Key 2026 | NCERTClasses.com

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📋 Answer Key Details

Board	RBSE, Ajmer
Class	11th
Subject	Computer Science
Subject Code	03
Session	2025-26
Theory Marks	70
Practical	30
MCQ Answers	✅ Complete
Python Code	✅ Full Programs
Truth Tables	✅ Complete

📄 CS Model Paper देखें →

यह RBSE Class 11 Computer Science Model Paper 2025-26 की सम्पूर्ण उत्तर कुंजी है। प्रश्न-पत्र देखने के लिए: CS Model Paper PDF →

💡 How to use: First attempt the paper yourself, then verify with this key. Python programs must be written with correct indentation. Sample programs shown here are model answers — alternate correct approaches also get full marks.

📑 Contents

Section A — Objective (20 M)
Section B — Short Answer (25 M)
Section C — Long Answer (25 M)
Marking Scheme

Section A — Objective Type Questions (20 Marks)

Q.1 — MCQ : Unit I — Computer Organisation 5 Marks

Q.1 — All MCQ Answers5 × 1 = 5

#	Question	Correct Answer	Reason
(i)	Ascending order of memory units	(a) Bit → Byte → KB → MB → GB → TB → PB	Each unit = 1024 of previous
(ii)	Volatile memory directly accessed by CPU	(b) Cache Memory	Fastest volatile memory between CPU & RAM
(iii)	NAND gate Boolean expression	(c) A · B	NAND = NOT(AND) = complement of A·B
(iv)	Decimal of (1011.101)₂	(a) 11.625	8+2+1=11; 0.5+0.125=0.625 → 11.625
(v)	Cloud model for developers (no infra)	(c) PaaS	Platform as a Service — e.g., Google App Engine

💡 Q.1(iv) Working: (1011.101)₂ = 1×2³+0×2²+1×2¹+1×2⁰ + 1×2⁻¹+0×2⁻²+1×2⁻³ = 8+0+2+1+0.5+0+0.125 = 11.625

Q.2 — MCQ : Unit II — Python Programming 8 Marks

Q.2 — All MCQ Answers8 × 1 = 8

#	Code / Question	Correct Answer	Explanation
(i)	`print(type(3.14))`	(b) <class 'float'>	3.14 is a floating-point literal
(ii)	Immutable data type in Python	(c) Tuple	Tuples cannot be modified after creation
(iii)	`len("Hello World")`	(b) 11	H-e-l-l-o-space-W-o-r-l-d = 11 characters
(iv)	`[1, 2, 3] * 2`	(b) [1, 2, 3, 1, 2, 3]	* operator repeats the list
(v)	Keyword to define a function	(c) def	def functionname(): is Python syntax
(vi)	`s="RAJASTHAN"; s[2:6]`	(c) JAST	Index: R=0,A=1,J=2,A=3,S=4,T=5 → s[2:6]="JAST"
(vii)	Same object in memory operator	(b) is	`is` = identity operator; `==` = equality
(viii)	`range(1, 10, 3)`	(c) 1, 4, 7	Start=1, step=3 → 1, 4, 7 (10 excluded)

💡 Q.2(vi) String Index: R(0) A(1) J(2) A(3) S(4) T(5) H(6) A(7) N(8) → s[2:6] takes index 2,3,4,5 = JAST

Q.3 — MCQ : Unit III — Society, Law & Ethics 2 Marks

Q.3 — Answers2 × 1 = 2

#	Question	Correct Answer
(i)	NOT a type of Intellectual Property Right	(d) Firewall — Firewall is a security tool, not an IPR
(ii)	Fraudulent emails to steal information	(b) Phishing — fake emails disguised as legitimate sources

Q.4 — Fill in the Blanks 3 Marks

Q.4 — Answers3 × 1 = 3

(i) Hexadecimal of (255)₁₀ = FF
255 ÷ 16 = 15 remainder 15 → F F → (FF)₁₆
(ii) Function to find number of elements in a list = len()
(iii) Law governing electronic commerce and cyber crimes in India = Information Technology Act (IT Act), 2000

Q.5 — True or False 3 Marks

Q.5 — Answers3 × 1 = 3

#	Statement	Answer
(i)	Compiler translates entire code at once; interpreter line by line	TRUE ✅
(ii)	In Python, a tuple can be modified after creation	❌ FALSE — Tuples are immutable
(iii)	De Morgan's Law: A+B = A·B	TRUE ✅ — Second De Morgan's Law

Q.6 — Match the Following 2 Marks

Q.6 — Correct Matches4 × ½ = 2

Column A	Matches With	Column B
(i) ASCII	→ (b)	7-bit encoding scheme for English characters
(ii) Dictionary	→ (a)	Python data structure storing key-value pairs
(iii) Machine Learning	→ (d)	Subset of AI that enables computers to learn from data
(iv) Ransomware	→ (c)	Software that locks files and demands ransom

Section B — Short Answer Type Questions (25 Marks)

Q.7 — Number System Conversions 3 Marks

Q.7 — Complete Solutions (Step-wise)3 Marks

📊 Marking: 1 mark each conversion | Steps must be shown for full marks

(a) (101110.11)₂ → Decimal

Integer part: 1×2⁵ + 0×2⁴ + 1×2³ + 1×2² + 1×2¹ + 0×2⁰ = 32 + 0 + 8 + 4 + 2 + 0 = 46 Fractional: 1×2⁻¹ + 1×2⁻² = 0.5 + 0.25 = 0.75 Answer: (101110.11)₂ = (46.75)₁₀

(b) (175)₁₀ → Hexadecimal

175 ÷ 16 = 10 remainder 15 → F 10 ÷ 16 = 0 remainder 10 → A Read remainders bottom to top: AF Answer: (175)₁₀ = (AF)₁₆

(c) (3F8)₁₆ → Binary (Direct conversion)

Each hex digit → 4 binary bits: 3 = 0011 F = 1111 8 = 1000 Answer: (3F8)₁₆ = (0011 1111 1000)₂ = (001111111000)₂

Q.8 — Boolean Logic & De Morgan's Law 3 Marks

Q.8 — Complete Truth Tables3 Marks

(a) Truth Table for F = A·B̄ + Ā·B (XOR)

A	B	Ā	B̄	A·B̄	Ā·B	F = A·B̄ + Ā·B	A⊕B
0	0	1	1	0	0	0	0 ✅
0	1	1	0	0	1	1	1 ✅
1	0	0	1	1	0	1	1 ✅
1	1	0	0	0	0	0	0 ✅

✅ Verified: F = A·B̄ + Ā·B produces same output as XOR gate (A⊕B).

(b) De Morgan's Law Verification (A=1, B=0)

First Law: A+B = A·B

LHS: A+B = 1+0 = 1 → NOT(1) = 0 RHS: Ā·B̄ = NOT(1)·NOT(0) = 0·1 = 0 LHS = RHS = 0 ✅ Verified

💡 Remember: De Morgan's 1st Law: NOT(A OR B) = NOT A AND NOT B | 2nd Law: NOT(A AND B) = NOT A OR NOT B

Q.9 — Python Basics 3 Marks

Q.9 — Answers3 Marks

(a) Interactive Mode vs Script Mode (1 Mark)

Interactive Mode	Script Mode
Type code directly at >>> prompt	Write complete program in .py file
Executed immediately, one line at a time	Entire file executed on running
Good for testing small expressions	Used for full programs & projects

(b) Output of the code (2 Marks)

x = 10 y = 3 print(x // y, x % y, x ** y)

3 1 1000

x // y = 10 // 3 = 3 (Floor division — quotient only)
x % y = 10 % 3 = 1 (Modulus — remainder)
x ** y = 10 ** 3 = 1000 (Exponentiation — 10³)

Q.10 — Flow of Control 3 Marks

Q.10 — Program + Output3 Marks

(a) Positive / Negative / Zero Program (2 Marks)

# Program to check Positive, Negative or Zero n = int(input("Enter a number: ")) if n > 0: print(n, "is Positive") elif n < 0: print(n, "is Negative") else: print("The number is Zero")

(b) Output of for loop with continue (1 Mark)

for i in range(1, 6): if i == 3: continue print(i, end=" ")

1 2 4 5

When i=3, continue skips the print statement and moves to next iteration. So 3 is not printed.

Q.11 — Python Strings 3 Marks

Q.11 — Answers3 Marks

(a) String Slicing (1 Mark)

String Slicing: Extracting a portion of a string using string[start:stop:step] syntax. It returns a new string without modifying the original.

"COMPUTER"[1:5:2] Index: C(0) O(1) M(2) P(3) U(4) T(5) E(6) R(7) start=1 → O, step=2 → skip M(2), take P(3)... wait Actually: index 1,3 (step 2 from 1 to 4) = s[1]='O', s[3]='P'

(b) String Built-in Functions Output (2 Marks)

s = " Hello World " print(s.strip()) # removes leading/trailing spaces print(s.upper()) # converts to uppercase print(s.replace("World", "Python")) # replaces substring print(s.split()) # splits on whitespace, returns list

Hello World HELLO WORLD Hello Python ['Hello', 'World']

💡 Note: upper() and replace() preserve original spaces. Only strip() removes them. split() ignores leading/trailing spaces automatically.

Q.12 — Python Lists 3 Marks

Q.12 — Answers3 Marks

(a) List Operations (1½ Marks)

L = [45, 12, 78, 34, 56, 90, 23] # (i) Append 100 L.append(100) # L = [45, 12, 78, 34, 56, 90, 23, 100] # (ii) Remove 34 L.remove(34) # L = [45, 12, 78, 56, 90, 23, 100] # (iii) Sort in descending order L.sort(reverse=True) print(L)

[100, 90, 78, 56, 45, 23, 12]

(b) Find Max & Min without max()/min() (1½ Marks)

L = [45, 12, 78, 34, 56, 90, 23] maximum = L[0] minimum = L[0] for num in L: if num > maximum: maximum = num if num < minimum: minimum = num print("Maximum:", maximum) print("Minimum:", minimum)

Maximum: 90 Minimum: 12

Q.13 — Tuples & Dictionaries 3 Marks

Q.13 — Answers3 Marks

(a) List vs Tuple (1 Mark)

List	Tuple
Mutable — can be changed after creation	Immutable — cannot be changed
Uses square brackets [ ]	Uses parentheses ( )
Slower due to dynamic nature	Faster, less memory
e.g. L = [1, 2, 3]	e.g. T = (1, 2, 3)

When to prefer Tuple: When data should not change — e.g., days of week, coordinates, RGB values.

(b) Dictionary Operations (2 Marks)

d = {'name':'Ravi', 'age':17, 'city':'Jodhpur'} # (i) Add new key 'score': 95 d['score'] = 95 # (ii) Delete key 'city' del d['city'] # (iii) Print all keys print(d.keys())

dict_keys(['name', 'age', 'score'])

Q.14 — Functions — Factorial 2 Marks

Q.14 — Factorial Function2 Marks

# Function to find factorial using for loop def factorial(n): fact = 1 for i in range(1, n+1): fact = fact * i return fact # Calling the function for n = 6 result = factorial(6) print("Factorial of 6 =", result)

Factorial of 6 = 720

Dry run: 1×1=1, ×2=2, ×3=6, ×4=24, ×5=120, ×6=720

Q.15 — Society, Law & Ethics (any two) 2 Marks

Q.15 — Model Answers (~35 words each)2 × 1 = 2

(a) Digital Footprint:
A digital footprint is the trail of data you leave while using the internet. Passive examples: (1) websites tracking your browsing history via cookies, (2) your location being recorded by apps without direct input.

(b) Copyright vs Patent:
Copyright protects original creative works (books, music, software) automatically upon creation — e.g., a novel. Patent protects inventions and grants exclusive rights to use/sell — e.g., a new medicine formula. Copyright is automatic; Patent requires registration.

(c) E-waste:
E-waste refers to discarded electronic devices (mobiles, computers, TVs). Improper disposal is dangerous because these contain toxic materials like lead, mercury, and cadmium that contaminate soil and groundwater, harming human health and ecosystems.

Q.16 — Python Modules 3 Marks

Q.16 — Answers3 Marks

(a) import math vs from math import sqrt (1 Mark)

import math	from math import sqrt
Imports entire math module	Imports only sqrt function
Access: `math.sqrt(4)`	Access: `sqrt(4)` directly
Uses more memory	Efficient — loads only what's needed

(b) Module Programs (2 Marks)

# (i) Square root using math module import math print("√144 =", math.sqrt(144)) # (ii) Random integer between 1 and 100 import random print("Random number:", random.randint(1, 100)) # (iii) Mean of [10, 20, 30, 40, 50] import statistics data = [10, 20, 30, 40, 50] print("Mean =", statistics.mean(data))

√144 = 12.0 Random number: [varies each run] Mean = 30

Section C — Long Answer Type Questions (25 Marks)

Q.17 — Computer Organisation / Encoding 5 Marks

Q.17 — Option A: Computer Organisation5 Marks

📊 Marking: Part (a) 3 marks (1 each) | Part (b) 2 marks

(a-i) Primary vs Secondary Memory (3 differences)

Primary Memory	Secondary Memory
Directly accessed by CPU	Not directly accessed by CPU
Volatile (RAM) or non-volatile (ROM)	Non-volatile — data persists
Faster, smaller capacity, costlier	Slower, larger capacity, cheaper
e.g. RAM, ROM, Cache	e.g. HDD, SSD, USB, DVD

(a-ii) System Software vs Application Software

System Software	Application Software
Manages hardware & system resources	Performs specific user tasks
e.g. OS, Device Drivers, Compilers	e.g. MS Word, Tally, Games
Works in background	Works for end-user

(a-iii) Compiler vs Interpreter

Compiler	Interpreter
Translates entire program at once	Translates line by line
Faster execution after compilation	Slower — translates each time
Error shown after full compilation	Stops at first error found
e.g. C, C++	e.g. Python, BASIC

(b) Five Functions of Operating System (2 Marks)

1. Process Management — Controls creation, scheduling & termination of processes.
2. Memory Management — Allocates and deallocates RAM to programs.
3. File Management — Organises files/folders; controls access & storage.
4. Device Management — Manages input/output devices via device drivers.
5. Security & Access Control — User authentication and data protection.

Explain any two (1 mark each): Memory Management: OS keeps track of which part of memory is in use by which process and allocates free memory. Process Management: OS uses scheduling algorithms (like Round Robin) to give CPU time to each running process.

Q.17 — Option B: Encoding + Logic Gates5 Marks

(a) Encoding Schemes (3 Marks)

Encoding	Full Form	Bits	Range/Characters
ASCII	American Standard Code for Information Interchange	7-bit	128 characters (0–127) — English letters, digits, symbols
ISCII	Indian Standard Code for Information Interchange	8-bit	256 characters — supports Indian scripts (Devanagari etc.)
UNICODE UTF-8	Universal Code — 8-bit variable	1–4 bytes	1,114,112 characters — all world languages; backward compatible with ASCII
UNICODE UTF-32	Universal Code — 32-bit fixed	4 bytes fixed	Same range as UTF-8 but fixed 4 bytes per character; uses more memory

(b) NAND and NOR Gate Truth Tables (2 Marks)

NAND Gate: F = A·B

A	B	F = A·B
0	0	1
0	1	1
1	0	1
1	1	0

NOR Gate: F = A+B

A	B	F = A+B
0	0	1
0	1	0
1	0	0
1	1	0

💡 Remember: NAND = output 0 only when both inputs are 1 | NOR = output 1 only when both inputs are 0. Both are Universal Gates.

Q.18 — Problem Solving & Flowchart 5 Marks

Q.18 — Steps + Flowchart + Pseudocode5 Marks

(a) Steps in Problem Solving (2 Marks)

Analysing the Problem — Understand input, output and constraints.
Developing an Algorithm — Write step-by-step logical solution.
Coding — Translate algorithm into a programming language.
Testing and Debugging — Run program, find and fix errors.
Decomposition — Break complex problem into smaller sub-problems.

(b) Flowchart + Pseudocode: Sum and Average of 10 Numbers (3 Marks)

📊 Flowchart:

          ┌─────────────┐
│    START    │
└──────┬──────┘
       ↓
┌─────────────┐
│ sum=0, i=1  │
└──────┬──────┘
       ↓
┌─────────────┐
│ INPUT num   │
└──────┬──────┘
       ↓
┌─────────────┐
│sum = sum+num│
│  i = i + 1  │
└──────┬──────┘
       ↓
◇ i <= 10 ? ◇
   YES ↙  ↘ NO
  (loop)   ↓
      ┌──────────────┐
      │avg = sum / 10│
      └──────┬───────┘
             ↓
      ┌──────────────┐
      │PRINT sum,avg │
      └──────┬───────┘
             ↓
         ┌───────┐
         │  STOP │
         └───────┘
        

📝 Pseudocode:

START SET sum = 0 SET i = 1 WHILE i <= 10: INPUT num sum = sum + num i = i + 1 END WHILE avg = sum / 10 PRINT "Sum =", sum PRINT "Average =", avg STOP

Python Program:

total = 0 for i in range(10): n = int(input("Enter number: ")) total += n avg = total / 10 print("Sum =", total) print("Average =", avg)

Q.19 — Python Programs — Loops / Patterns 5 Marks

Q.19 — Option A: Pattern + Series5 Marks

(a) Star Triangle Pattern (2½ Marks)

# Printing triangle star pattern for i in range(1, 6): for j in range(1, i+1): print("*", end=" ") print()

* * * * * * * * * * * * * * *

(b) Sum of Squares S = 1² + 2² + ... + n² (2½ Marks)

# Sum of squares series n = int(input("Enter value of n: ")) S = 0 for i in range(1, n+1): S = S + i**2 print("Sum of squares =", S)

Enter value of n: 5 Sum of squares = 55

Verification: 1+4+9+16+25 = 55 ✅

Q.19 — Option B: Prime + Linear Search5 Marks

(a) Prime Number Check (2½ Marks)

# Program to check Prime number n = int(input("Enter a number: ")) flag = True if n < 2: flag = False else: for i in range(2, n): if n % i == 0: flag = False break if flag: print(n, "is a Prime number") else: print(n, "is NOT a Prime number")

(b) Linear Search (2½ Marks)

# Linear Search Program n = int(input("How many numbers? ")) lst = [] for i in range(n): x = int(input("Enter number: ")) lst.append(x) target = int(input("Enter value to search: ")) found = False for i in range(len(lst)): if lst[i] == target: print("Found at index", i) found = True break if not found: print("Not Found")

Q.20 — Functions + Strings 5 Marks

Q.20 — Complete Answers5 Marks

(a) count_vowels() function (2½ Marks)

# Function to count vowels in a string def count_vowels(s): vowels = "aeiouAEIOU" count = 0 for ch in s: if ch in vowels: count += 1 return count # Test text = "Computer Science Rajasthan" print("Vowel count =", count_vowels(text))

Vowel count = 9

Vowels: o, u, e, i, e, a, a, a, a = 9 vowels ✅

(b) Local vs Global Variables (2½ Marks)

Local Variable	Global Variable
Declared inside a function	Declared outside all functions
Accessible only within that function	Accessible throughout the program
Destroyed when function ends	Exists for entire program lifetime

# Demonstrating global keyword count = 0 # global variable def increment(): global count # declare count as global count += 1 print("Inside function: count =", count) increment() increment() print("Outside function: count =", count)

Inside function: count = 1 Inside function: count = 2 Outside function: count = 2

Q.21 — Sorting / Dictionary Programs 5 Marks

Q.21 — Option A: Bubble Sort5 Marks

(a) Bubble Sort Dry Run on [64, 25, 12, 22, 11] (3 Marks)

Algorithm: Compare adjacent elements; if left > right, swap. Repeat for n-1 passes.

Pass	Step-by-step comparison	Array after pass
Pass 1	64↔25✓, 64↔12✓, 64↔22✓, 64↔11✓	[25, 12, 22, 11, 64]
Pass 2	25↔12✓, 25↔22✓, 25↔11✓	[12, 22, 11, 25, 64]
Pass 3	12↔22✗, 22↔11✓	[12, 11, 22, 25, 64]
Pass 4	12↔11✓	[11, 12, 22, 25, 64]

Sorted: [11, 12, 22, 25, 64]

(b) bubble_sort() Function (2 Marks)

def bubble_sort(lst): n = len(lst) for i in range(n-1): for j in range(n-1-i): if lst[j] > lst[j+1]: lst[j], lst[j+1] = lst[j+1], lst[j] return lst arr = [64, 25, 12, 22, 11] print(bubble_sort(arr))

[11, 12, 22, 25, 64]

Q.21 — Option B: Dictionary + Insertion Sort5 Marks

(a) Student Marks Dictionary Program (3 Marks)

# Dictionary of students and their marks students = {} n = int(input("Enter number of students: ")) for i in range(n): name = input("Enter name: ") marks = int(input("Enter marks: ")) students[name] = marks # (i) Student with highest marks top = max(students, key=students.get) print("Highest scorer:", top, "→", students[top]) # (ii) Count students above 75 above75 = sum(1 for m in students.values() if m > 75) print("Students above 75:", above75)

(b) Insertion Sort (2 Marks)

Algorithm: Pick each element and insert it into its correct position in the already-sorted part.

# Insertion Sort for [5, 3, 8, 1, 9] lst = [5, 3, 8, 1, 9] for i in range(1, len(lst)): key = lst[i] j = i - 1 while j >= 0 and lst[j] > key: lst[j+1] = lst[j] j -= 1 lst[j+1] = key print("Sorted:", lst)

Sorted: [1, 3, 5, 8, 9]

Marking Scheme Summary

📊 Complete Marks DistributionTheory 70 Marks

Section	Questions	Topics	Marks
A	Q.1–6	MCQ + Fill Blanks + True/False + Match	20
B	Q.7–16	Number System + Boolean + Python + Society	25
C	Q.17–21	Long Answer + Programs + Sorting	25
Theory Total			70
Practical (Lab Test 12 + Report 7 + Viva 3 + Project 8)			30
Grand Total			100

💡 Score More — Python Tips:

Always write comments in programs — examiners reward well-documented code.
Indentation carries marks in Python — 4 spaces per level, consistently.
Show dry run / output even if not asked — demonstrates understanding.
In number conversions, always show step-by-step working for full marks.
Truth tables: draw complete table with all intermediate columns for Boolean expressions.

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RBSE Class 11 Computer Science Answer Key 2026 | कक्षा 11 कंप्यूटर विज्ञान उत्तर कुंजी 2026

RBSE Class 11 Computer Science — Model Paper Answer Key 2025-26 Complete Solution | Python Programs | Marking Scheme | Subject Code 03