Knowledge Check: Module 20 - Complete Python

1. How do you create an empty dictionary in Python?

empty_dict = []

empty_dict = {}

empty_dict = ()

empty_dict = dict[]

2. Given the dictionary student = {'name': 'Alex', 'age': 20}, how do you access the value associated with the key 'name'?

student('name')

student['name']

student.get('name') (Select the primary way taught in this intro)

student{name}

3. What happens if you try to access a key that does *not* exist in a dictionary using square brackets, like my_dict['unknown_key']?

It returns None.

It automatically adds the key with a default value.

It raises a KeyError.

It returns an empty string "".

4. How can you add a new key-value pair ('city': 'London') to an existing dictionary called user_info?

user_info.append({'city': 'London'})

user_info['city'] = 'London'

user_info.add('city', 'London')

user_info + {'city': 'London'}

5. What is the primary purpose of a dictionary in Python?

To store an ordered sequence of items.

To store items that cannot be changed (immutable).

To store key-value pairs, allowing fast lookups by key.

To perform mathematical calculations.

6. Consider prefs = {'color': 'blue', 'size': 'M'}. What happens if you execute prefs['color'] = 'red'?

It adds a new key 'color' with the value 'red'.

It causes an error because the key 'color' already exists.

It updates the value associated with the key 'color' to 'red'.

It creates a completely new dictionary.

7. Which data type is commonly used for dictionary *keys*?

Lists

Strings and Numbers (Immutable types)

Other Dictionaries

Any data type can be a key.

8. What are the components of a key-value pair in a dictionary?

An index and an element

A key and a value, separated by a colon (:)

Two values separated by a comma (,)

A function name and its result

9. Is the order of items guaranteed in dictionaries created in older Python versions (before 3.7)?

Yes, they are always ordered by key.

Yes, they are always ordered by insertion time.

No, the order was arbitrary and could change.

Yes, they are always ordered alphabetically by value.

10. Can a dictionary store values of different data types (e.g., strings, numbers, lists) together?

Yes, dictionary values can be of any type.

No, all values in a dictionary must be of the same type.

Only strings and numbers are allowed as values.

Only immutable types (like numbers, strings, tuples) are allowed as values.

20 Knowledge Check: Dictionaries Intro