Why lists are used in Python - Test Your Understanding

Practice - 5 Tasks

1fill in blank

easy

Complete the code to create a list of fruits.

Python

fruits = [[1]]

Drag options to blanks, or click blank then click option'

A'apple', 'banana', 'cherry'

B'apple banana cherry'

C'apple'; 'banana'; 'cherry'

D'apple' + 'banana' + 'cherry'

Attempts:

3 left

💡 Hint

Common Mistakes

Forgetting commas between items

Using spaces instead of commas

Using plus signs to join items

Lists hold multiple items separated by commas inside square brackets.

2fill in blank

medium

Complete the code to access the first item in the list.

Python

first_fruit = fruits[[1]]

Drag options to blanks, or click blank then click option'

A1

B-1

C0

D2

Attempts:

3 left

💡 Hint

Common Mistakes

Using 1 instead of 0 for the first item

Using negative indexes without understanding

List indexes start at 0, so the first item is at index 0.

3fill in blank

hard

Fix the error in the code to add an item to the list.

Python

fruits.[1]('orange')

Drag options to blanks, or click blank then click option'

Aadd

Bextend

Cinsert

Dappend

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'add' which is not a list method

Using 'extend' which expects an iterable

Using 'insert' without specifying position

The append method adds a single item to the end of a list.

4fill in blank

hard

Fill both blanks to create a list of squares for numbers greater than 3.

Python

squares = [x[1]2 for x in range(1, 6) if x [2] 3]

Drag options to blanks, or click blank then click option'

A**

B>

C<

D*

Attempts:

3 left

💡 Hint

Common Mistakes

Using multiplication instead of power

Using less than instead of greater than

Use ** to square numbers and > to filter numbers greater than 3.

5fill in blank

hard

Fill all three blanks to create a dictionary of uppercase words with their lengths if length is more than 4.

Python

result = [1]: [2] for word in words if len(word) [3] 4}

Drag options to blanks, or click blank then click option'

Aword.upper()

Blen(word)

C>

Dword

Attempts:

3 left

💡 Hint

Common Mistakes

Using word instead of word.upper() for keys

Using < instead of > for filtering

Using word instead of len(word) for values

The dictionary keys are uppercase words, values are their lengths, filtered by length greater than 4.

Practice

1. Why do we use lists in Python?

easy

A. To store multiple items in one variable

B. To store only one item at a time

C. To perform mathematical calculations only

D. To create functions

Solution

1. Step 1: Understand the purpose of lists

   Lists are designed to hold many items together in one place.

2. Step 2: Compare options with list features

   Only To store multiple items in one variable correctly states that lists store multiple items in one variable.

3. Final Answer:

   To store multiple items in one variable -> Option A

4. Quick Check:

   Lists hold many items = To store multiple items in one variable [OK]

Hint: Lists hold many items together in one variable [OK]

Common Mistakes:

• Thinking lists store only one item
• Confusing lists with functions
• Assuming lists are for math only

2. Which of the following is the correct way to create a list in Python?

easy

A. my_list = [1, 2, 3]

B. my_list = (1, 2, 3)

C. my_list = {1, 2, 3}

D. my_list = <1, 2, 3>

Solution

1. Step 1: Recall list syntax in Python

   Lists are created using square brackets [] around items.

2. Step 2: Match options with correct syntax

   my_list = [1, 2, 3] uses square brackets, so it is correct. Others use parentheses, curly braces, or angle brackets which are incorrect for lists.

3. Final Answer:

   my_list = [1, 2, 3] -> Option A

4. Quick Check:

   Lists use [] brackets = my_list = [1, 2, 3] [OK]

Hint: Lists use square brackets [] to hold items [OK]

Common Mistakes:

• Using parentheses () which create tuples
• Using curly braces {} which create sets or dicts
• Using angle brackets <> which are invalid

3. What will be the output of this code?

fruits = ['apple', 'banana', 'cherry']
print(fruits[1])

medium

A. apple

B. IndexError

C. cherry

D. banana

Solution

1. Step 1: Understand list indexing

   Python lists start indexing at 0, so fruits[1] is the second item.

2. Step 2: Identify the item at index 1

   The list is ['apple', 'banana', 'cherry'], so index 1 is 'banana'.

3. Final Answer:

   banana -> Option D

4. Quick Check:

   fruits[1] = banana [OK]

Hint: List indexes start at 0, so index 1 is second item [OK]

Common Mistakes:

• Thinking index starts at 1
• Confusing list with dictionary
• Expecting an error for valid index

4. Find the error in this code that tries to add an item to a list:

my_list = [1, 2, 3]
my_list.add(4)
print(my_list)

medium

A. Missing brackets in print statement

B. Using add() instead of append() to add item

C. List cannot hold numbers

D. List must be declared with curly braces

Solution

1. Step 1: Identify method to add items to list

   Python lists use append() to add items, not add().

2. Step 2: Check the code for method usage

   The code uses my_list.add(4), which causes an error because add() is not a list method.

3. Final Answer:

   Using add() instead of append() to add item -> Option B

4. Quick Check:

   Use append() to add items to list [OK]

Hint: Use append() to add items to lists, not add() [OK]

Common Mistakes:

• Using add() which is for sets
• Thinking lists can't hold numbers
• Incorrect print syntax assumptions

5. You have a list of student names and want to add a new student, remove one who left, and keep the order. Which data structure should you use and why?

hard

A. Use a dictionary because it stores key-value pairs

B. Use a set because it automatically sorts items

C. Use a list because it keeps order and allows adding/removing items

D. Use a tuple because it is immutable

Solution

1. Step 1: Understand requirements for data structure

   The data structure must keep order and allow adding/removing students.

2. Step 2: Match requirements with data structure features

   Lists keep order and allow adding/removing items. Sets do not keep order. Dictionaries store key-value pairs, not just items. Tuples are immutable and cannot be changed.

3. Final Answer:

   Use a list because it keeps order and allows adding/removing items -> Option C

4. Quick Check:

   Lists keep order and are changeable [OK]

Hint: Lists keep order and allow changes, perfect for student lists [OK]

Common Mistakes:

• Choosing sets which don't keep order
• Confusing dictionaries with lists
• Using tuples which cannot be changed