NCERT Class 11 Informatics Practices Informatics Practices: Chapter 4 — Working with Lists and Dictionaries
This chapter introduces students to the fundamental data structures of lists and dictionaries in Python, crucial for Informatics Practices. It begins with an in-depth explanation of lists, defining them as ordered, mutable sequences that can hold elements of various data types, enclosed in square brackets. The chapter details how to access list elements using positive and negative indexing, illustrating with examples. It covers list operations, traversal, and various built-in methods and functions for manipulation. Subsequently, the text introduces dictionaries as unordered collections of key-value pairs, also mutable and capable of holding diverse data types. Students will learn about dictionary traversal and methods for manipulation. Understanding these concepts is vital for efficient data handling and problem-solving in programming, supporting the CBSE curriculum.
Quick info
| Board | CBSE / NCERT |
|---|---|
| Class | Class 11 |
| Subject | Informatics Practices |
| Book | Informatics Practices |
| Chapter | Chapter 4 — Working with Lists and Dictionaries |
| Language | English |
| PDF type | NCERT Textbook |
| Session | CBSE 2026 |
| Reading time | 2 minutes |
| Word count | 380 |
Learning outcomes
- Understand the concept of lists as ordered, mutable sequences.
- Access and manipulate list elements using indexing.
- Learn about various list operations, methods, and built-in functions.
- Grasp the concept of dictionaries as unordered key-value pairs.
- Traverse and manipulate dictionary elements.
Vocabulary
| Word | Meaning |
|---|---|
| List | An ordered, mutable sequence of elements, enclosed in square brackets. |
| Mutable | Capable of being changed after creation. |
| Index | A numerical position of an element in a list, starting from 0. |
| Nested List | A list that contains other lists as its elements. |
| Dictionary | An unordered collection of key-value pairs. |
| Key-value pair | A pair of associated items in a dictionary, where a unique key maps to a value. |
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Practice questions
- What is the main difference between a string and a list in Python? Answer: A string consists only of characters, while a list can contain elements of different data types.
- How are elements accessed in a list? Answer: Elements are accessed using their index value, enclosed in square brackets, starting from 0 for the first element.
- What does it mean for a list to be mutable? Answer: It means that the contents of the list can be changed after it has been created.
- What is a nested list? Answer: A nested list is a list that contains other lists as its elements.
- How do you access the last element of a list using negative indexing? Answer: You use the index -1 to access the last element.
Practice MCQs
Q1. Which of the following is NOT a characteristic of a Python list?
Explanation: Lists in Python are mutable and ordered, and they can contain elements of different data types, not just the same data type.
Q2. What symbol is used to enclose elements of a list in Python?
Explanation: List elements are always enclosed within square brackets [] in Python.
Q3. If `my_lis[10, 20, 30, 40]`, what will `my_list[1]` return?
Explanation: The index 1 refers to the second element in the list, which is 20.
Q4. What does `my_list[-1]` return for `my_lis[10, 20, 30, 40]`?
Explanation: Negative indexing starts from the end of the list. -1 refers to the last element, which is 40.
Q5. Which data structure is an unordered collection of key-value pairs?
Explanation: Dictionaries in Python are defined as unordered collections where data is stored in key-value pairs.
Frequently asked questions
What is a list in Python?
A list is an ordered, mutable sequence that can contain elements of different data types, enclosed in square brackets.
How do you create a list in Python?
You create a list by enclosing comma-separated elements within square brackets, e.g., `my_list = [1, 'hello', 3.14]`.
Can a list contain elements of different data types?
Yes, a Python list can hold elements of various data types, such as integers, floats, strings, and even other lists.
What is the difference between positive and negative indexing in lists?
Positive indexing starts from 0 for the first element and increases. Negative indexing starts from -1 for the last element and decreases towards the beginning.
What is a dictionary in Python?
A dictionary is an unordered collection of data values, used to store data values like a map, which, unlike other Data Types that hold only a single value as an element, Dictionary holds key:value pair.
Are lists ordered or unordered?
Lists are ordered sequences, meaning the order of elements is preserved and can be accessed by their index.
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NCERT Class 11 Informatics Practices — Informatics Practices — Chapter 4 — Working with Lists and Dictionaries. Verified by NCERT Help Editorial Team. Reviewed on 29 Jul 2026. Last updated 10 Aug 2026.