Class 11 Computer Science Chapter 9 Lists – NCERT Solutions & PDF Download

Exercise Solutions: NCERT Solutions Computer Science Chapter 9 Lists (2025-26)

1. What will be the output of the following statements?

1. list1 = [12,32,65,26,80,10]
   list1.sort()
   print(list1)
   

   Answer: [10, 12, 26, 32, 65, 80]

   
   

2. list1 = [12,32,65,26,80,10]
   sorted(list1)
   print(list1)
   

   Answer: [12, 32, 65, 26, 80, 10]

   
   

3. list1 = [1,2,3,4,5,6,7,8,9,10]
   list1[::-2]
   list1[:3] + list1[3:]
   

   Answer:

   • list1[::-2] gives [10, 8, 6, 4, 2]
   • list1[:3] + list1[3:] gives [1, 2, 3, 4, 5, 6, 7, 8, 9, 10] (the original list)

4. list1 = [1,2,3,4,5]
   list1[len(list1)-1]
   

   Answer: 5

2. Consider the following list myList. What will be the elements of myList after the following two operations:

myList = [10,20,30,40]
i. myList.append([50,60])
ii. myList.extend([80,90])

Answer:
After i. myList.append([50,60]) → [10, 20, 30, 40, [50, 60]]
After ii. myList.extend([80,90]) → [10, 20, 30, 40, [50, 60], 80, 90]

3. What will be the output of the following code segment:

myList = [1,2,3,4,5,6,7,8,9,10]
for i in range(0,len(myList)):
    if i%2 == 0:
        print(myList[i])

Answer:

• 1
• 3
• 5
• 7
• 9

4. What will be the output of the following code segment:

1. myList = [1,2,3,4,5,6,7,8,9,10]
   del myList[3:]
   print(myList)
   

   Answer: [1, 2, 3]

   
   

2. myList = [1,2,3,4,5,6,7,8,9,10]
   del myList[:5]
   print(myList)
   

   Answer: [6, 7, 8, 9, 10]

   
   

3. myList = [1,2,3,4,5,6,7,8,9,10]
   del myList[::2]
   print(myList)
   

   Answer: [2, 4, 6, 8, 10]

5. Differentiate between append() and extend() functions of list.

6. Consider a list:

list1 = [6,7,8,9]

What is the difference between the following operations on list1:

1. list1 * 2
   Answer: This creates a new list: [6, 7, 8, 9, 6, 7, 8, 9]. It does not modify list1 itself.
2. list1 *= 2
   Answer: This modifies list1 in-place, doubling the elements so list1 becomes [6, 7, 8, 9, 6, 7, 8, 9].
3. list1 = list1 * 2
   Answer: This also results in list1 equal to [6, 7, 8, 9, 6, 7, 8, 9], same as above.

7. The record of a student (Name, Roll No., Marks in five subjects and percentage of marks) is stored in the following list:

stRecord = ['Raman','A-36',[56,98,99,72,69], 78.8]

Write Python statements to retrieve the following:

• Percentage of the student: stRecord[3]
  Output: 78.8
• Marks in the fifth subject: stRecord[2][4]
  Output: 69
• Maximum marks of the student: max(stRecord[2])
  Output: 99
• Roll no. of the student: stRecord[1]
  Output: 'A-36'
• Change the name of the student from ‘Raman’ to ‘Raghav’: stRecord[0] = 'Raghav'

Programming Problems

1. Write a program to find the number of times an element occurs in the list.
   

   Answer: Use the count() method:
   

   mylist = [10, 20, 10, 30, 10, 50]
   element = 10
   print(mylist.count(element))
   # Output: 3
       

2. Write a program to read a list of n integers (positive as well as negative). Create two new lists, one having all positive numbers and the other having all negative numbers from the given list. Print all three lists.
   

   Answer:
   

   lst = []
   pos = []
   neg = []
   n = int(input("Enter the number of elements: "))
   for i in range(n):
       num = int(input())
       lst.append(num)
       if num >= 0:
           pos.append(num)
       else:
           neg.append(num)
   print("All:", lst)
   print("Positive:", pos)
   print("Negative:", neg)
       

3. Write a function that returns the largest element of the list passed as parameter.
   

   Answer:

   def largest(lst):
       return max(lst)
       

4. Write a function to return the second largest number from a list of numbers.
   

   Answer:

   def second_largest(lst):
       lst1 = list(set(lst))
       lst1.sort(reverse=True)
       return lst1[1] if len(lst1) > 1 else None
       

5. Write a program to read a list of n integers and find their median.
   Note: The median value of a list of values is the middle one when they are arranged in order. If there are two middle values then take their average.
   

   Answer:

   lst = []
   n = int(input("Enter n: "))
   for i in range(n):
       lst.append(int(input()))
   lst.sort()
   if n % 2 != 0:
       median = lst[n // 2]
   else:
       median = (lst[n//2 - 1] + lst[n//2]) / 2
   print("Median:", median)
       

6. Write a program to read a list of elements. Modify this list so that it does not contain any duplicate elements, i.e., all elements occurring multiple times in the list should appear only once.
   

   Answer:

   lst = [10, 20, 10, 30, 20, 10, 50, 30]
   lst = list(set(lst))
   print(lst)
       

7. Write a program to read a list of elements. Input an element from the user that has to be inserted in the list. Also input the position at which it is to be inserted. Write a user defined function to insert the element at the desired position in the list.
   

   Answer:

   def insert_at(lst, element, pos):
       lst.insert(pos, element)
   lst = [10, 20, 30, 40]
   el = int(input("Element to insert: "))
   p = int(input("Position: "))
   insert_at(lst, el, p)
   print(lst)
       

8. Write a program to read elements of a list.
   a) The program should ask for the position of the element to be deleted from the list. Write a function to delete the element at the desired position in the list.
   b) The program should ask for the value of the element to be deleted from the list. Write a function to delete the element of this value from the list.
   

   Answer:
   

   # a)
   def delete_at_position(lst, pos):
       if 0 <= pos < len(lst):
           lst.pop(pos)
   lst = [10, 20, 30, 40]
   p = int(input("Position to delete: "))
   delete_at_position(lst, p)
   print(lst)
   # b)
   def delete_by_value(lst, val):
       if val in lst:
           lst.remove(val)
   lst = [10, 20, 30, 40]
   v = int(input("Value to delete: "))
   delete_by_value(lst, v)
   print(lst)
       

9. Read a list of n elements. Pass this list to a function which reverses this list in-place without creating a new list.
   

   Answer:

   def reverse_list(lst):
       lst.reverse()
   lst = [10, 20, 30, 40]
   reverse_list(lst)
   print(lst)
       

Mastering Python Lists: NCERT Solutions for Chapter 9

Understanding Python Lists is crucial for scoring well in Computer Science. This chapter introduces you to list creation, advanced operations, and methods, helping you solve every type of Python list question confidently in exams.

Practicing NCERT Solutions Computer Science Chapter 9 Lists ensures you get familiar with list manipulation, searching, and nested lists. These are key topics in board and entrance tests, so focus on the core concepts and code examples provided in your textbook.

For best results, write and execute list-based Python programs regularly. Reviewing these solutions, formulas, and methods will help you quickly solve MCQs, code outputs, and conceptual problems across competitive exams and term assessments.