Python Dictionary Practice Questions with Solutions

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Dictionaries store data as key-value pairs in Python. They are useful for organizing, retrieving, and updating data efficiently. In this Python Dictionary Practice Questions with Solutions set, you’ll learn dictionary creation, accessing values, updating items, removing elements, and common dictionary methods through beginner-friendly practice questions.

1. Python Program to Create and Print a Dictionary

Problem Statement

Write a Python program to create a dictionary containing a student’s name, age, and course, then print it.

Python Solution

student = {
    "name": "John",
    "age": 20,
    "course": "Python"
}

print(student)

Sample Output

{'name': 'John', 'age': 20, 'course': 'Python'}

Explanation

A dictionary stores data in key-value pairs using curly braces {}.

Concepts Covered

  • Dictionary Creation
  • Key-Value Pairs

2. Python Program to Access a Dictionary Value

Problem Statement

Write a Python program to print the value of the "course" key.

Python Solution

student = {
    "name": "John",
    "age": 20,
    "course": "Python"
}

print(student["course"])

Sample Output

Python

Explanation

Values can be accessed using their corresponding keys.

Concepts Covered

  • Dictionary Access

3. Python Program to Add a New Key-Value Pair

Problem Statement

Write a Python program to add a new key "city" with the value "Delhi" to a dictionary.

Python Solution

student = {
    "name": "John",
    "age": 20
}

student["city"] = "Delhi"

print(student)

Sample Output

{'name': 'John', 'age': 20, 'city': 'Delhi'}

Explanation

Assigning a new key automatically adds it to the dictionary.

Concepts Covered

  • Adding Items

4. Python Program to Update a Dictionary Value

Problem Statement

Write a Python program to update the age of a student from 20 to 21.

Python Solution

student = {
    "name": "John",
    "age": 20
}

student["age"] = 21

print(student)

Sample Output

{'name': 'John', 'age': 21}

Explanation

Assigning a new value to an existing key updates that value.

Concepts Covered

  • Updating Dictionary Values

5. Python Program to Remove an Item from a Dictionary

Problem Statement

Write a Python program to remove the "age" key from a dictionary.

Python Solution

student = {
    "name": "John",
    "age": 20,
    "course": "Python"
}

student.pop("age")

print(student)

Sample Output

{'name': 'John', 'course': 'Python'}

Explanation

The pop() method removes the specified key and its value.

Concepts Covered

  • pop()

6. Python Program to Print All Dictionary Keys

Problem Statement

Write a Python program to print all keys of a dictionary.

Python Solution

student = {
    "name": "John",
    "age": 20,
    "course": "Python"
}

print(student.keys())

Sample Output

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

Explanation

The keys() method returns all dictionary keys.

Concepts Covered

  • keys()

7. Python Program to Print All Dictionary Values

Problem Statement

Write a Python program to print all values of a dictionary.

Python Solution

student = {
    "name": "John",
    "age": 20,
    "course": "Python"
}

print(student.values())

Sample Output

dict_values(['John', 20, 'Python'])

Explanation

The values() method returns all values stored in the dictionary.

Concepts Covered

  • values()

8. Python Program to Print All Key-Value Pairs

Problem Statement

Write a Python program to print all key-value pairs in a dictionary.

Python Solution

student = {
    "name": "John",
    "age": 20,
    "course": "Python"
}

for key, value in student.items():
    print(key, ":", value)

Sample Output

name : John
age : 20
course : Python

Explanation

The items() method returns both keys and values together.

Concepts Covered

  • items()
  • for Loop

9. Python Program to Check Whether a Key Exists

Problem Statement

Write a Python program to check whether the key "course" exists in a dictionary.

Python Solution

student = {
    "name": "John",
    "age": 20,
    "course": "Python"
}

if "course" in student:
    print("Key Found")
else:
    print("Key Not Found")

Sample Output

Key Found

Explanation

The in operator checks whether a key exists in the dictionary.

Concepts Covered

  • Membership Operator

10. Python Program to Count the Total Number of Key-Value Pairs

Problem Statement

Write a Python program to count the total number of key-value pairs in a dictionary.

Python Solution

student = {
    "name": "John",
    "age": 20,
    "course": "Python",
    "city": "Delhi"
}

print("Total Items:", len(student))

Sample Output

Total Items: 4

Explanation

The len() function returns the total number of key-value pairs in the dictionary.

Concepts Covered

  • len()
  • Dictionary Size

11. Python Program to Find the Student with the Highest Marks

Problem Statement

Write a Python program to find the student who has scored the highest marks using a dictionary.

Python Solution

students = {
    "Rahul": 85,
    "Priya": 92,
    "Aman": 78,
    "Neha": 95,
    "Rohit": 88
}

top_student = max(students, key=students.get)

print("Top Student:", top_student)
print("Highest Marks:", students[top_student])

Sample Output

Top Student: Neha
Highest Marks: 95

Explanation

The max() function with key=students.get returns the key whose value is the highest.

Concepts Covered

  • Dictionary
  • max()
  • Dictionary Methods
  • Key-Value Pairs

12. Python Program to Merge Two Dictionaries and Add Common Values

Problem Statement

Write a Python program to merge two dictionaries. If a key exists in both dictionaries, add their values together.

Python Solution

dict1 = {
    "A": 10,
    "B": 20,
    "C": 30
}

dict2 = {
    "B": 15,
    "C": 25,
    "D": 40
}

result = dict1.copy()

for key, value in dict2.items():
    if key in result:
        result[key] += value
    else:
        result[key] = value

print(result)

Sample Output

{'A': 10, 'B': 35, 'C': 55, 'D': 40}

Explanation

The program copies the first dictionary and updates it using the second dictionary. Common keys have their values added together.

Concepts Covered

  • Dictionary Merge
  • items()
  • copy()
  • Conditional Statements

13. Python Program to Invert a Dictionary

Problem Statement

Write a Python program to swap the keys and values of a dictionary.

Python Solution

student = {
    "Rahul": 101,
    "Priya": 102,
    "Neha": 103
}

inverted = {}

for key, value in student.items():
    inverted[value] = key

print(inverted)

Sample Output

{101: 'Rahul', 102: 'Priya', 103: 'Neha'}

Explanation

The program creates a new dictionary by making each value a key and each key a value.

Concepts Covered

  • Dictionary Traversal
  • items()
  • Dictionary Creation

14. Python Program to Group Words by Their Length

Problem Statement

Write a Python program to group words according to their length using a dictionary.

Python Solution

words = ["apple", "bat", "banana", "cat", "orange", "dog"]

groups = {}

for word in words:
    length = len(word)

    if length not in groups:
        groups[length] = []

    groups[length].append(word)

print(groups)

Sample Output

{
3: ['bat', 'cat', 'dog'],
5: ['apple'],
6: ['banana', 'orange']
}

Explanation

Each word is stored in a list based on its length. The dictionary key represents the word length.

Concepts Covered

  • Dictionary
  • Lists
  • append()
  • len()

15. Python Program to Count the Frequency of Words in a Sentence

Problem Statement

Write a Python program to count the occurrence of every word in a sentence.

Python Solution

sentence = input("Enter a sentence: ")

words = sentence.lower().split()

frequency = {}

for word in words:
    frequency[word] = frequency.get(word, 0) + 1

print("\nWord Frequency:")

for word, count in frequency.items():
    print(word, ":", count)

Sample Output

Enter a sentence:
Python is easy and Python is powerful

Word Frequency:
python : 2
is : 2
easy : 1
and : 1
powerful : 1

Explanation

The sentence is converted into lowercase and split into individual words. The get() method counts the frequency of each word efficiently.

Concepts Covered

  • Dictionaries
  • split()
  • get()
  • Word Frequency Analysis

16. Python Program to Sort a Dictionary by Values in Descending Order

Problem Statement

Write a Python program to sort a dictionary based on its values in descending order.

Python Solution

students = {
    "Rahul": 78,
    "Priya": 95,
    "Aman": 88,
    "Neha": 91,
    "Rohit": 82
}

sorted_dict = dict(
    sorted(
        students.items(),
        key=lambda item: item[1],
        reverse=True
    )
)

print("Dictionary Sorted by Values:")
print(sorted_dict)

Sample Output

Dictionary Sorted by Values:
{'Priya': 95, 'Neha': 91, 'Aman': 88, 'Rohit': 82, 'Rahul': 78}

Explanation

The sorted() function sorts dictionary items using their values, and reverse=True arranges them in descending order.

Concepts Covered

  • sorted()
  • lambda Function
  • Dictionary Sorting

17. Python Program to Find Keys with Duplicate Values

Problem Statement

Write a Python program to find all keys that share duplicate values in a dictionary.

Python Solution

employee = {
    "Rahul": "Python",
    "Priya": "Java",
    "Aman": "Python",
    "Neha": "SQL",
    "Rohit": "Java"
}

duplicates = {}

for key, value in employee.items():
    duplicates.setdefault(value, []).append(key)

print("Keys with Duplicate Values:")

for value, keys in duplicates.items():
    if len(keys) > 1:
        print(value, ":", keys)

Sample Output

Keys with Duplicate Values:
Python : ['Rahul', 'Aman']
Java : ['Priya', 'Rohit']

Explanation

The program groups keys according to their values and prints only those groups that contain more than one key.

Concepts Covered

  • setdefault()
  • Dictionary Grouping
  • Lists

18. Python Program to Create a Nested Dictionary from Two Lists

Problem Statement

Write a Python program to create a nested dictionary using two lists: one for student names and another for marks.

Python Solution

students = ["Rahul", "Priya", "Aman"]
marks = [85, 92, 78]

result = {}

for i in range(len(students)):
    result[students[i]] = {
        "Marks": marks[i]
    }

print(result)

Sample Output

{
'Rahul': {'Marks': 85},
'Priya': {'Marks': 92},
'Aman': {'Marks': 78}
}

Explanation

The program creates a nested dictionary where each student’s name becomes a key and their marks are stored inside another dictionary.

Concepts Covered

  • Nested Dictionary
  • Lists
  • Looping
  • Dictionary Creation

19. Python Program to Find the Average Value of a Dictionary

Problem Statement

Write a Python program to calculate the average of all numeric values stored in a dictionary.

Python Solution

sales = {
    "January": 25000,
    "February": 32000,
    "March": 28000,
    "April": 35000
}

average = sum(sales.values()) / len(sales)

print("Average Sales:", average)

Sample Output

Average Sales: 30000.0

Explanation

The values() method returns all dictionary values. Their sum is divided by the total number of entries to calculate the average.

Concepts Covered

  • values()
  • sum()
  • len()
  • Dictionary Calculations

20. Python Program to Find the Most Frequently Occurring Value in a Dictionary

Problem Statement

Write a Python program to determine which value appears most frequently in a dictionary.

Python Solution

products = {
    "Laptop": "Electronics",
    "Mobile": "Electronics",
    "Chair": "Furniture",
    "Table": "Furniture",
    "TV": "Electronics",
    "Bed": "Furniture",
    "Watch": "Electronics"
}

frequency = {}

for value in products.values():
    frequency[value] = frequency.get(value, 0) + 1

most_common = max(frequency, key=frequency.get)

print("Most Frequent Value:", most_common)
print("Count:", frequency[most_common])

Sample Output

Most Frequent Value: Electronics
Count: 4

Explanation

The program counts the occurrence of each dictionary value using another dictionary and then finds the value with the highest frequency using max().

Concepts Covered

  • Dictionary Values
  • Frequency Counting
  • get()
  • max()
  • Dictionary Traversal

21. Python Program to Create an Inventory Management System Using Dictionaries

Problem Statement

Write a Python program to create a simple inventory management system using dictionaries. Display the available stock and calculate the total inventory value.

Python Solution

inventory = {
    "Laptop": {"Price": 55000, "Quantity": 8},
    "Mouse": {"Price": 600, "Quantity": 30},
    "Keyboard": {"Price": 1200, "Quantity": 20},
    "Monitor": {"Price": 15000, "Quantity": 6}
}

total_value = 0

print("Inventory Details\n")

for item, details in inventory.items():
    value = details["Price"] * details["Quantity"]
    total_value += value

    print(f"{item}")
    print(f"Price: ₹{details['Price']}")
    print(f"Quantity: {details['Quantity']}")
    print(f"Total Value: ₹{value}\n")

print("Overall Inventory Value: ₹", total_value)

Sample Output

Inventory Details

Laptop
Price: ₹55000
Quantity: 8
Total Value: ₹440000

Mouse
Price: ₹600
Quantity: 30
Total Value: ₹18000

Keyboard
Price: ₹1200
Quantity: 20
Total Value: ₹24000

Monitor
Price: ₹15000
Quantity: 6
Total Value: ₹90000

Overall Inventory Value: ₹572000

Explanation

The inventory is stored as a nested dictionary. Each product contains its own price and quantity. The program calculates the total value of every product and the overall inventory.

Concepts Covered

  • Nested Dictionary
  • Dictionary Traversal
  • Arithmetic Operations
  • Real-world Project

22. Python Program to Find the Employee with the Highest Salary

Problem Statement

Write a Python program to find the employee who has the highest salary from a nested dictionary.

Python Solution

employees = {
    "Rahul": {"Salary": 55000},
    "Priya": {"Salary": 72000},
    "Aman": {"Salary": 68000},
    "Neha": {"Salary": 81000}
}

highest = max(
    employees,
    key=lambda emp: employees[emp]["Salary"]
)

print("Highest Paid Employee:", highest)
print("Salary:", employees[highest]["Salary"])

Sample Output

Highest Paid Employee: Neha
Salary: 81000

Explanation

The program uses the max() function with a lambda expression to compare employee salaries.

Concepts Covered

  • Nested Dictionary
  • max()
  • lambda Function

23. Python Program to Reverse Key-Value Pairs with Duplicate Values

Problem Statement

Write a Python program to reverse a dictionary. If multiple keys have the same value, store them together in a list.

Python Solution

student = {
    "Rahul": "Python",
    "Aman": "Python",
    "Priya": "Java",
    "Neha": "SQL",
    "Rohit": "Java"
}

reverse = {}

for key, value in student.items():

    if value not in reverse:
        reverse[value] = []

    reverse[value].append(key)

print(reverse)

Sample Output

{
'Python': ['Rahul', 'Aman'],
'Java': ['Priya', 'Rohit'],
'SQL': ['Neha']
}

Explanation

Unlike a normal dictionary inversion, this program preserves duplicate values by storing multiple keys inside a list.

Concepts Covered

  • Nested Lists
  • Dictionary
  • Grouping Data

24. Python Program to Compare Two Dictionaries and Display the Differences

Problem Statement

Write a Python program to compare two dictionaries and display keys whose values are different.

Python Solution

dict1 = {
    "Python": 95,
    "Java": 80,
    "SQL": 90
}

dict2 = {
    "Python": 95,
    "Java": 88,
    "SQL": 85
}

for key in dict1:

    if dict1[key] != dict2[key]:
        print(key)
        print("Dictionary 1:", dict1[key])
        print("Dictionary 2:", dict2[key])
        print()

Sample Output

Java
Dictionary 1: 80
Dictionary 2: 88

SQL
Dictionary 1: 90
Dictionary 2: 85

Explanation

The program compares corresponding values in two dictionaries and prints only those keys where the values differ.

Concepts Covered

  • Dictionary Comparison
  • Loops
  • Conditional Statements

25. Python Program to Build a Simple Student Result Management System

Problem Statement

Write a Python program to calculate the total marks, average marks, and grade of each student stored in a nested dictionary.

Python Solution

students = {
    "Rahul": {"Math": 85, "Science": 90, "English": 88},
    "Priya": {"Math": 95, "Science": 98, "English": 94},
    "Aman": {"Math": 72, "Science": 76, "English": 80}
}

for name, marks in students.items():

    total = sum(marks.values())
    average = total / len(marks)

    if average >= 90:
        grade = "A"
    elif average >= 75:
        grade = "B"
    else:
        grade = "C"

    print("Student:", name)
    print("Total:", total)
    print("Average:", round(average, 2))
    print("Grade:", grade)
    print("-" * 25)

Sample Output

Student: Rahul
Total: 263
Average: 87.67
Grade: B
-------------------------

Student: Priya
Total: 287
Average: 95.67
Grade: A
-------------------------

Student: Aman
Total: 228
Average: 76.0
Grade: B
-------------------------

Explanation

The program uses a nested dictionary to store subject-wise marks, calculates the total and average for each student, and assigns grades based on the average marks.

Concepts Covered

  • Nested Dictionary
  • sum()
  • values()
  • Conditional Statements
  • Real-world Student Management System

Frequently Asked Questions (FAQs)

1. What is a dictionary in Python?

A dictionary is a built-in Python data structure that stores data as key-value pairs. Each key in a dictionary must be unique, while values can be of any data type. Dictionaries are mutable, meaning you can add, update, or remove elements after creation.

Example:

student = {
    "Name": "Rahul",
    "Age": 21,
    "Course": "Python"
}

print(student)

2. What is the difference between a dictionary and a list in Python?

DictionaryList
Stores data as key-value pairsStores ordered elements
Accessed using keysAccessed using indexes
Keys must be uniqueDuplicate elements are allowed
Faster lookup using keysSequential lookup using indexes
Enclosed in {}Enclosed in []

Dictionaries are best when you need fast access to data using meaningful keys, while lists are ideal for ordered collections.

3. How do you add, update, and delete elements in a dictionary?

You can modify dictionaries easily because they are mutable.

Example:

student = {
    "Name": "Rahul",
    "Age": 21
}

# Add
student["City"] = "Delhi"

# Update
student["Age"] = 22

# Delete
del student["City"]

print(student)

4. What are the most commonly used dictionary methods in Python?

Some frequently used dictionary methods include:

  • get()
  • keys()
  • values()
  • items()
  • update()
  • pop()
  • popitem()
  • setdefault()
  • copy()
  • clear()
  • fromkeys()

These methods simplify dictionary operations and improve code readability.

5. What is a nested dictionary?

A nested dictionary is a dictionary that contains one or more dictionaries as its values. It is useful for storing structured or hierarchical data.

Example:

employees = {
    "Rahul": {
        "Age": 24,
        "Department": "IT"
    },
    "Priya": {
        "Age": 26,
        "Department": "HR"
    }
}

print(employees)

Nested dictionaries are commonly used in JSON data, APIs, and database applications.

6. What is the difference between get() and square bracket [] notation?

Both are used to retrieve dictionary values, but they behave differently.

  • dictionary[key] raises a KeyError if the key does not exist.
  • dictionary.get(key) returns None (or a default value if provided) instead of raising an error.

Example:

student = {
    "Name": "Rahul"
}

print(student.get("Age"))
print(student.get("Age", "Not Available"))

Using get() is generally safer when you’re unsure whether a key exists.

7. Can dictionary keys be duplicated?

No. Dictionary keys must always be unique. If the same key is assigned more than once, the latest value overwrites the previous one.

Example:

data = {
    "Python": 90,
    "Python": 95
}

print(data)

Output:

{'Python': 95}

8. Where are dictionaries used in real-world Python applications?

Dictionaries are widely used in many software applications, including:

  • JSON and API responses
  • Student Management Systems
  • Employee Databases
  • Inventory Management
  • Banking Applications
  • Machine Learning
  • Data Analysis
  • Web Development
  • Configuration Files
  • E-commerce Applications

They are one of the most commonly used data structures in professional Python development.

9. What is the average time complexity of dictionary operations?

Python dictionaries are implemented using hash tables, making most operations very efficient.

OperationAverage Time Complexity
Access ValueO(1)
Insert KeyO(1)
Update ValueO(1)
Delete KeyO(1)
Search KeyO(1)
Iterate DictionaryO(n)

This fast lookup capability is one of the biggest advantages of dictionaries.

10. Why are dictionaries important for Python interviews?

Dictionary-based questions are among the most frequently asked in Python interviews because they test your understanding of:

  • Hash tables
  • Key-value data structures
  • Nested dictionaries
  • Data manipulation
  • Searching and grouping
  • Frequency counting
  • JSON processing
  • Algorithm optimization
  • Real-world problem-solving

Mastering dictionaries is essential for careers in Python development, Data Science, Machine Learning, Automation, Web Development, and Backend Engineering. Strong knowledge of dictionary operations will help you write efficient, scalable, and interview-ready Python programs.

Chapter Summary

After completing this chapter, you have learned:

  • Dictionary creation
  • Accessing values
  • Adding key-value pairs
  • Updating dictionary values
  • Removing items using pop()
  • keys()
  • values()
  • items()
  • Checking whether a key exists
  • Counting dictionary items

Written by Shubhranshu Shekhar, who has trained 20000+ students in coding.

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