NCERT Solutions For Class 11 Computer Science Chapter 5 Getting Started With Python - 2025-26

question:

1. Which of the following identifier names are invalid and why?
i Serial_no. v Total_Marks
ii 1st_Room vi total-Marks
iii Hundred$
vii _Percentage
iv Total Marks 

viii True

answer:

• Serial_no. — Invalid (dot . not allowed in identifiers).

• 1st_Room — Invalid (cannot start with a digit).

• Hundred$ — Invalid ($ not allowed in Python identifiers).

• Total Marks — Invalid (spaces not allowed).

• Total_Marks — Valid (letters + underscore).

• total-Marks — Invalid (- is minus operator, not allowed in identifiers).

• _Percentage — Valid (leading underscore is allowed).

• True — Invalid (reserved boolean literal in Python).

question:

2. Write the corresponding Python assignment statements: 

a) Assign 10 to variable length and 20 to variable breadth. 

b) Assign the average of values of variables length and breadth to a variable sum. 

c) Assign a list containing strings ‘Paper’, ‘Gel Pen’, and ‘Eraser’ to a variable stationery. d) Assign the strings ‘Mohandas’, ‘Karamchand’, and ‘Gandhi’ to variables first, middle and last. 

e) Assign the concatenated value of string variables first, middle and last to variable fullname. Make sure to incorporate blank spaces appropriately between different parts of names.

answer:

length = 10 breadth = 20

sum = (length + breadth) / 2

stationery = ['Paper', 'Gel Pen', 'Eraser']

first = 'Mohandas'
middle = 'Karamchand'
last = 'Gandhi'

fullname = first + ' ' + middle + ' ' + last

question:

3. Write logical expressions corresponding to the following statements in Python and evaluate the expressions (assuming variables num1, num2, num3, first, middle, last are already having meaningful values): 

a) The sum of 20 and –10 is less than 12. 

b) num3 is not more than 24. 

c) 6.75 is between the values of integers num1 and num2. 

d) The string ‘middle’ is larger than the string ‘first’ and smaller than the string ‘last’. 

e) List Stationery is empty.

answer:

1. 20 + (-10) < 12 ⇒ True.

2. num3 <= 24 ⇒ depends on value of num3.

3. min(num1, num2) < 6.75 < max(num1, num2) ⇒ depends on num1, num2.

4. ('middle' > 'first') and ('middle' < 'last') ⇒ False (since 'middle' < 'last' is False).

5. not Stationery (or len(Stationery) == 0) ⇒ True if list is empty.

question:

4. Add a pair of parentheses to each expression so that it evaluates to True. 

a) 0 == 1 == 2 

b) 2 + 3 == 4 + 5 == 7 

c) 1 < -1 == 3 > 4

answer:

2. 0 == (1 == 2) ⇒ 0 == False ⇒ True.

3. No placement of a single pair of parentheses makes 2 + 3 == 4 + 5 == 7 True in Python.

4. (1 < -1) == (3 > 4) ⇒ False == False ⇒ True.

question:

5. Write the output of the following: 

a) num1 = 4 num2 = num1 + 1 num1 = 2 print (num1, num2) 

b) num1, num2 = 2, 6 num1, num2 = num2, num1 + 2 print (num1, num2) 

c) num1, num2 = 2, 3 num3, num2 = num1, num3 + 1 print (num1, num2, num3)

answer:

1. Output: 2 5

2. Output: 6 4

3. Raises NameError: name 'num3' is not defined (so no output).

question:

6. Which data type will be used to represent the following data values and why? 

a) Number of months in a year 

b) Resident of Delhi or not 

c) Mobile number 

d) Pocket money 

e) Volume of a sphere 

f) Perimeter of a square 

g) Name of the student 

h) Address of the student

answer:

1. int — whole number, fixed count (12).

2. bool — True/False.

3. str — treated as text (leading zeros, no arithmetic).

4. float (or Decimal for currency accuracy) — can have fractions.

5. float — measurement may be fractional.

6. float — may be fractional depending on side.

7. str — text.

8. str — multi-word text.

question:

7. Give the output of the following when num1 = 4, num2 = 3, num3 = 2 

a) num1 += num2 + num3 print (num1) 

b) num1 = num1 ** (num2 + num3) print (num1) 

c) num1 **= num2 + num3 

d) num1 = '5' + '5' print(num1) 

e) print(4.00/(2.0+2.0)) 

f) num1 = 2+9*((3*12)-8)/10 print(num1) 

g) num1 = 24 // 4 // 2 print(num1) 

h) num1 = float(10) print (num1) 

i) num1 = int('3.14') print (num1) 

j) print('Bye' == 'BYE') 

k) print(10 != 9 and 20 >= 20) 

l) print(10 + 6 * 2 ** 2 != 9//4 -3 and 29 >= 29/9) 

m) print(5 % 10 + 10 < 50 and 29 <= 29) 

n) print((0 < 6) or (not(10 == 6) and (10<0)))

answer:

1. 9

2. 1024

3. No output; updates num1 to 1024.

4. 55

5. 1.0

6. 27.2

7. 3

8. 10.0

9. Raises ValueError: invalid literal for int() with base 10: '3.14'

10. False

11. True

12. True

13. True

14. True

question:

8. Categorise the following as syntax error, logical error or runtime error: 

a) 25 / 0 

b) num1 = 25; num2 = 0; num1/num2

answer:

1. Runtime error (ZeroDivisionError).

2. Runtime error (ZeroDivisionError).

question:

9. A dartboard of radius 10 units and the wall it is hanging on are represented using a two-dimensional coordinate system, with the board’s center at coordinate (0,0). Variables x and y store the x-coordinate and the y-coordinate of a dart that hits the dartboard. Write a Python expression using variables x and y that evaluates to True if the dart hits (is within) the dartboard, and then evaluate the expression for these dart coordinates: 

a) (0,0) 

b) (10,10) 

c) (6, 6) 

d) (7,8)

answer:

Expression: x**2 + y**2 <= 10**2

1. (0,0) ⇒ 0 <= 100 ⇒ True

2. (10,10) ⇒ 200 <= 100 ⇒ False

3. (6,6) ⇒ 72 <= 100 ⇒ True

4. (7,8) ⇒ 113 <= 100 ⇒ False

question:

10. Write a Python program to convert temperature in degree Celsius to degree Fahrenheit. If water boils at 100 degree C and freezes as 0 degree C, use the program to find out what is the boiling point and freezing point of water on the Fahrenheit scale. (Hint: T(°F) = T(°C) × 9/5 + 32)

answer:

c = float(input("Enter °C: ")) f = c * 9/5 + 32 print("°F:", f)
Using the formula:
100°C → 212°F, 0°C → 32°F

Boiling point: 212°F   |   Freezing point: 32°F

question:

11. Write a Python program to calculate the amount payable if money has been lent on simple interest. Principal or money lent = P, Rate of interest = R% per annum and Time = T years. Then Simple Interest (SI) = (P x R x T)/ 100. 

Amount payable = Principal + SI. P, R and T are given as input to the program.

answer:

P = float(input("Principal: ")) R = float(input("Rate (% per annum): ")) T = float(input("Time (years): ")) SI = (P * R * T) / 100 amount = P + SI print("Simple Interest:", SI) print("Amount Payable:", amount) 

question:

12. Write a program to calculate in how many days a work will be completed by three persons A, B and C together. A, B, C take x days, y days and z days respectively to do the job alone. The formula to calculate the number of days if they work together is xyz/(xy + yz + xz) days where x, y, and z are given as input to the program.

answer:

x = float(input("Days A takes: ")) y = float(input("Days B takes: ")) z = float(input("Days C takes: ")) days_together = (x * y * z) / (x * y + y * z + x * z) print("Days to finish together:", days_together) 

question:

13. Write a program to enter two integers and perform all arithmetic operations on them.

answer:

a = int(input("First integer: ")) b = int(input("Second integer: "))

print("Add:", a + b)
print("Sub:", a - b)
print("Mul:", a * b)
print("Div:", a / b) # true division
print("Floor Div:", a // b) # floor division
print("Mod:", a % b)
print("Pow:", a ** b)

question:

14. Write a program to swap two numbers using a third variable.

answer:

a = int(input("a: ")) b = int(input("b: ")) temp = a a = b b = temp print("a =", a, "b =", b) 

question:

15. Write a program to swap two numbers without using a third variable.

answer:

a = int(input("a: ")) b = int(input("b: ")) a, b = b, a print("a =", a, "b =", b) 

question:

16. Write a program to repeat the string ‘‘GOOD MORNING” n times. Here ‘n’ is an integer entered by the user.

answer:

n = int(input("n: ")) for _ in range(n): print("GOOD MORNING") 

question:

17. Write a program to find average of three numbers.

answer:

a = float(input("a: ")) b = float(input("b: ")) c = float(input("c: ")) avg = (a + b + c) / 3 print("Average:", avg) 

question:

18. The volume of a sphere with radius r is 4/3πr3. Write a Python program to find the volume of spheres with radius 7cm, 12cm, 16cm, respectively.

answer:

import math

for r in (7, 12, 16):
V = (4/3) * math.pi * (r ** 3)
print(f"r = {r} cm → Volume = {V:.2f} cm³")

Results:
r=7 → 1436.76 cm³
r=12 → 7238.23 cm³
r=16 → 17157.28 cm³

question:

19. Write a program that asks the user to enter their name and age. Print a message addressed to the user that tells the user the year in which they will turn 100 years old.

answer:

from datetime import date name = input("Name: ") age = int(input("Age: ")) current_year = date.today().year turn_100_year = current_year + (100 - age) print(f"Hello {name}, you will turn 100 in the year {turn_100_year}.") 

question:

20. The formula E = mc2 states that the equivalent energy (E) can be calculated as the mass (m) multiplied by the speed of light (c = about 3×108 m/s) squared. Write a program that accepts the mass of an object and determines its energy.

answer:

m = float(input("Mass (kg): ")) c = 3e8 E = m * c * c print("Energy (Joules):", E) 

question:

21. Presume that a ladder is put upright against a wall. Let variables length and angle store the length of the ladder and the angle that it forms with the ground as it leans against the wall. Write a Python program to compute the height reached by the ladder on the wall for the following values of length and angle: 

a) 16 feet and 75 degrees 

b) 20 feet and 0 degrees 

c) 24 feet and 45 degrees 

d) 24 feet and 80 degrees

answer:

import math

def height(length, angle_degrees):
return length * math.sin(math.radians(angle_degrees))

cases = [(16, 75), (20, 0), (24, 45), (24, 80)]
for L, A in cases:
print(f"L={L} ft, A={A}° → height = {height(L, A):.2f} ft")

Results:
16 ft @ 75° → 15.45 ft
20 ft @ 0° → 0.00 ft
24 ft @ 45° → 16.97 ft
24 ft @ 80° → 23.64 ft

Case Study-based Question
1. Schools use a Student Management Information System (SMIS) to manage student-related data.
This system provides facilities for:

• Recording and maintaining personal details of students.
  
  

• Maintaining marks scored in assessments and computing results.
  
  

• Keeping track of student attendance.
  
  

• Managing other student-related data.
  
  

Let us automate this process step by step.

Task:
Identify the personal details of students from your school identity card and write a Python program to:

1. Accept these details for all students of your school.
   
   

2. Display the details in the following format:
   
   

   

Answer:
# Program to accept and display student details

school_name = input("Enter School Name: ")

student_name = input("Enter Student Name: ")

roll_no = input("Enter Roll Number: ")

student_class = input("Enter Class: ")

section = input("Enter Section: ")

address1 = input("Enter Address Line 1: ")

address2 = input("Enter Address Line 2: ")

city = input("Enter City: ")

pincode = input("Enter Pin Code: ")

contact = input("Enter Parent's/Guardian's Contact No: ")

print("\n" + school_name.center(60))

print()

print(f"Student Name: {student_name:<20} Roll No: {roll_no}")

print(f"Class: {student_class:<26} Section: {section}")

print(f"Address :  {address1}")

print(f"           {address2}")

print()

print(f"City: {city:<25} Pin Code: {pincode}")

print(f"Parent’s/ Guardian’s Contact No: {contact}")

Sample Output:

ABC Public School

Student Name: PQR            Roll No: 99

Class: XI                    Section: A

Address :  Address Line 1 Address Line 2

City: ABC                    Pin Code: 999999

Parent’s/ Guardian’s Contact No: 9999999999

Getting Started with Python: Concepts and Tips

Explore the basics of Python programming from Class 11 NCERT with step-by-step explanations. Mastering Python variables, data types, and operators is essential for building a strong foundation in Computer Science for the 2025-26 syllabus.

With clear solutions for all important topics—keywords, identifiers, input/output, and debugging techniques—students can quickly resolve doubts and strengthen understanding. Keep practicing code examples to boost your exam preparation!

Regular revision and attempting exercise-based Python questions will make you confident for Computer Science exams. Use this chapter’s structured answers to sharpen your concepts and maximize your NCERT Class 11 score.

CBSE Class 11 Computer Science Chapter-wise NCERT Solutions

CBSE Class 11 Computer Science Study Materials