List creation and representation in Python - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to create a list named fruits with three items: 'apple', 'banana', and 'cherry'.

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

Using parentheses instead of square brackets creates a tuple, not a list.

Using curly braces creates a set, which is unordered.

Writing items without brackets creates a syntax error.

Lists in Python are created using square brackets []. So, ['apple', 'banana', 'cherry'] is the correct way to create a list with these items.

2fill in blank

medium

Complete the code to create an empty list named numbers.

Python

numbers = [1]

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

A[]

B()

C{}

D''

Attempts:

3 left

💡 Hint

Common Mistakes

Using parentheses creates an empty tuple, not a list.

Using curly braces creates an empty dictionary, not a list.

Using empty quotes creates an empty string.

An empty list is created with empty square brackets [].

3fill in blank

hard

Fix the error in the code to correctly create a list named colors with 'red', 'green', and 'blue'.

Python

colors = [1]

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

A['red', 'green', 'blue']

B{'red', 'green', 'blue'}

C('red', 'green', 'blue')

D'red', 'green', 'blue'

Attempts:

3 left

💡 Hint

Common Mistakes

Using parentheses instead of square brackets.

Using curly braces which create a set.

Listing items without brackets causes syntax errors.

The code must use square brackets to create a list. Parentheses create tuples, curly braces create sets, and just commas create a syntax error.

4fill in blank

hard

Fill both blanks to create a list of squares for numbers 1 to 5 using list comprehension.

Python

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

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

A**2

B>

C<=

D*2

Attempts:

3 left

💡 Hint

Common Mistakes

Using *2 instead of **2 for squaring.

Using <= instead of > in the condition.

Forgetting the exponent operator.

The expression x**2 calculates the square of x. The condition x > 3 filters numbers greater than 3.

5fill in blank

hard

Fill all three blanks to create a dictionary where keys are uppercase words and values are their lengths, but only for words longer than 4 letters.

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 word instead of len(word) for values.

Using <= or < instead of > in the condition.

The key is the uppercase word using word.upper(). The value is the length with len(word). The condition filters words longer than 4 letters using >.

Practice

1. Which of the following is the correct way to create an empty list in Python?

easy

A. ()

B. {}

C. []

D. list()

Solution

1. Step 1: Understand list syntax

   In Python, lists are created using square brackets [] or the list() function.

2. Step 2: Identify empty list creation

   [] is the literal syntax for an empty list, while list() also creates an empty list but is a function call.

3. Final Answer:

   [] -> Option C

4. Quick Check:

   Empty list = [] [OK]

Hint: Empty lists use square brackets [] directly [OK]

Common Mistakes:

• Using curly braces {} which create sets or dictionaries
• Using parentheses () which create tuples
• Confusing list() function with empty list literal

2. Which of the following is the correct syntax to create a list with the items 1, 2, and 3?

easy

A. list = [1, 2, 3]

B. list = <1, 2, 3>

C. list = {1, 2, 3}

D. list = (1, 2, 3)

Solution

1. Step 1: Recognize list syntax

   Lists in Python use square brackets [] to hold items in order.

2. Step 2: Check each option

   list = [1, 2, 3] uses square brackets with items 1, 2, 3 correctly. list = (1, 2, 3) uses parentheses which create tuples. list = {1, 2, 3} uses curly braces which create sets. list = <1, 2, 3> uses invalid syntax.

3. Final Answer:

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

4. Quick Check:

   List with items = [1, 2, 3] [OK]

Hint: Lists use square brackets [] with commas between items [OK]

Common Mistakes:

• Using parentheses () which create tuples
• Using curly braces {} which create sets
• Using invalid angle bracket syntax

3. What is the output of the following code?

my_list = [10, 'apple', 3.5]
print(my_list)

medium

A. [10, 'apple', 3.5]

B. (10, 'apple', 3.5)

C. {10, 'apple', 3.5}

D. 10, 'apple', 3.5

Solution

1. Step 1: Understand list contents and print

   The list my_list contains an integer, a string, and a float. Lists can hold mixed types.

2. Step 2: Print shows list with square brackets

   Printing a list shows its contents inside square brackets with commas separating items.

3. Final Answer:

   [10, 'apple', 3.5] -> Option A

4. Quick Check:

   Print list shows square brackets [OK]

Hint: Printed lists show square brackets and commas [OK]

Common Mistakes:

• Confusing list output with tuple or set syntax
• Expecting output without brackets
• Misreading quotes around strings

4. The following code is intended to create a list with numbers 1 to 3, but it causes an error. What is the problem?

numbers = [1, 2, 3
print(numbers)

medium

A. Using quotes around numbers

B. Using parentheses instead of square brackets

C. Missing commas between numbers

D. Missing closing square bracket ]

Solution

1. Step 1: Check list syntax

   The list starts with [ but does not have a closing ] bracket.

2. Step 2: Identify syntax error

   Missing the closing bracket causes a syntax error when Python tries to parse the list.

3. Final Answer:

   Missing closing square bracket ] -> Option D

4. Quick Check:

   Lists need matching brackets [OK]

Hint: Always match opening and closing brackets [] [OK]

Common Mistakes:

• Forgetting to close the list with ]
• Confusing brackets with parentheses
• Missing commas between items

5. You want to create a list that contains the numbers 1 to 5, but only even numbers should be included. Which code correctly creates this list?

hard

A. evens = [x for x in range(1, 6) if x % 2 != 0]

B. evens = [x for x in range(1, 6) if x % 2 == 0]

C. evens = [x for x in range(1, 5) if x % 2 == 1]

D. evens = [x for x in range(2, 7) if x % 2 == 1]

Solution

1. Step 1: Understand list comprehension with condition

   The code uses a list comprehension to select numbers from 1 to 5 (range(1, 6)) and filters only even numbers where x % 2 == 0.

2. Step 2: Check each option's condition and range

   evens = [x for x in range(1, 6) if x % 2 == 0] correctly uses range 1 to 5 and selects even numbers. Other options select odd numbers or wrong ranges.

3. Final Answer:

   evens = [x for x in range(1, 6) if x % 2 == 0] -> Option B

4. Quick Check:

   Even numbers filtered with x % 2 == 0 [OK]

Hint: Use list comprehension with if condition for filtering [OK]

Common Mistakes:

• Using wrong range limits
• Filtering odd numbers instead of even
• Confusing modulo condition