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Informatics PracticesClass 11Working with Chapter Lists and Dictionaries

Working with Chapter Lists and Dictionaries | Class 11 Informatics Practices Notes

By ConceptScroll Team · Published on 17 July 2026 · 3 min read

Working with Chapter Lists and Dictionaries – this guide gives you a concise, exam-ready overview of Working with Chapter Lists and Dictionaries from Class 11 Informatics Practices, written by ConceptScroll editors and reviewed against the latest NCERT textbook.

4.1 INTRODUCTION TO LIST

In Python programming, a list is a fundamental data type that represents an ordered sequence of elements. Unlike strings, which are sequences of characters, lists can contain elements of different data types such as integers, floats, strings, tuples, or even other lists, making them versatile for grouping mixed data. Lists are mutable, meaning their contents can be changed after creation. Elements in a list are enclosed within square brackets [ ] and separated by commas. This allows easy grouping and manipulation of data items. For example, a list of even numbers can be represented as [2, 4, 6, 8, 10, 12], and a list of vowels as ['a', 'e', 'i', 'o', 'u']. Lists can also be nested, meaning a list can contain other lists as elements, such as [['Physics', 101], ['Chemistry', 202], ['Mathematics', 303]]. This feature is useful for representing complex data structures. Lists maintain the order of elements, which means the sequence in which elements are added is preserved. This property is essential when the order of data matters. Lists are widely used in programming for tasks such as storing collections of items, iterating over data, and performing various operations like adding, removing, or modifying elements.

📊 Diagram: The chapter's opening diagram visually represents lists as sequences of elements enclosed in square brackets, showing examples of lists with integers, characters, and nested lists to illustrate the concept of ordered and mutable sequences.

🧪 Activity: No specific activity in this section.

🔗 Connection: This section introduces lists, setting the foundation for subsequent sections on list operations, traversal, and methods.

Frequently asked questions

1. What will be the output of the following statements? a) list1 = [12,32,65,26,80,10] list1.sort() print(list1) b) list1 = [12,32,65,26,80,10] sorted(list1) print(list1) c) list1 = [1,2,3,4,5,6,7,8,9,10] list1[::-2] list1[:3] + list1[3:] d) list1 = [1,2,3,4,5] list1[len(list1)-1]

a) list1.sort() sorts the list in place. So after sorting, list1 becomes [10, 12, 26, 32, 65, 80]. The print statement outputs: [10, 12, 26, 32, 65, 80]

b) sorted(list1) returns a new sorted list but does not modify list1 itself. Since the returned sorted list is not assigned, list1 remains unchanged. So print(list1) outputs: [12, 32, 65, 26, 80, 10]

c) list1[::-2] returns a slice starting from the end towards the start, stepping by 2. So it picks elements at indices 9,7,5,3,1 (0-based): [10,8

2. Consider the following list myList. What will be the elements of myList after each of the following operations? myList = [10,20,30,40] a) myList.append([50,60]) b) myList.extend([80,90])

Initial list: myList = [10, 20, 30, 40]

a) myList.append([50,60]) adds the entire list [50,60] as a single element at the end. So myList becomes: [10, 20, 30, 40, [50, 60]]

b) myList.extend([80,90]) adds each element of the list [80,90] individually to the end of myList. So after extending, myList becomes: [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])

The code iterates over indices 0 to 9 of myList. For each index i, if i is even (i%2 == 0), it prints myList[i]. Indices 0,2,4,6,8 are even. Corresponding elements are: 1, 3, 5, 7, 9. Hence, output will be: 1 3 5 7 9

4. What will be the output of the following code segment? a) myList = [1,2,3,4,5,6,7,8,9,10] del myList[3:] print(myList) b) myList = [1,2,3,4,5,6,7,8,9,10] del myList[:5] print(myList) c) myList = [1,2,3,4,5,6,7,8,9,10] del myList[::2] print(myList)

a) del myList[3:] deletes elements from index 3 to end. Original list: [1,2,3,4,5,6,7,8,9,10] After deletion: [1,2,3] Output: [1, 2, 3]

b) del myList[:5] deletes elements from start to index 4. Original list: [1,2,3,4,5,6,7,8,9,10] After deletion: [6,7,8,9,10] Output: [6, 7, 8, 9, 10]

c) del myList[::2] deletes elements at indices 0,2,4,6,8. Original list: [1,2,3,4,5,6,7,8,9,10] Elements at indices 0,2,4,6,8 are 1,3,5,7,9. After deletion, remaining elements are at indices 1,3,5,7,9: 2,4,6,8,10

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