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Quiz: Lists — Basics

Test your understanding of Python lists, indexing, slicing, and mutability with these questions. Click "Show Answer" to reveal the correct answer and explanation.

1. How do you create a list in Python that holds three colors?

  1. colors = {"red", "green", "blue"}
  2. colors = ("red", "green", "blue")
  3. colors = ["red", "green", "blue"]
  4. colors = "red, green, blue"
Show Answer

The correct answer is C. Lists in Python are created using square brackets [] with items separated by commas. Option A creates a set (curly braces), option B creates a tuple (parentheses), and option D is just a single string — not a collection of separate items.

Concept Tested: List Type

2. Given scores = [95, 87, 100, 73], what does scores[2] return?

  1. 87
  2. 73
  3. 95
  4. 100
Show Answer

The correct answer is D. Python uses zero-based indexing: index 0 is 95, index 1 is 87, index 2 is 100, and index 3 is 73. A very common mistake is to assume index 2 is the second item, but it is actually the third item (counting from zero).

Concept Tested: List Indexing

3. Given colors = ["red", "green", "blue", "yellow"], what does colors[-1] return?

  1. "red" (the first item)
  2. An error, because negative indexes are invalid for lists
  3. "green" (the second item)
  4. "yellow" (the last item)
Show Answer

The correct answer is D. Negative indexes count from the end of the list. Index -1 is the last item, -2 is second-to-last, and so on. For ["red", "green", "blue", "yellow"], colors[-1] is "yellow". This is useful when you want the last item without knowing the list's length.

Concept Tested: Negative Indexing

4. What does scores[1:3] return for scores = [95, 87, 100, 73]?

  1. [87, 100, 73]
  2. [87, 100]
  3. [95, 87, 100]
  4. [100, 73]
Show Answer

The correct answer is B. List slicing [start:end] returns items from index start up to but NOT including index end. scores[1:3] gives items at indexes 1 and 2: [87, 100]. The item at index 3 (73) is not included. This is the same rule as string slicing.

Concept Tested: List Slicing

5. What does len(["apple", "banana", "kiwi"]) return?

  1. 15 (the total number of characters in all words)
  2. 2
  3. 3
  4. 0
Show Answer

The correct answer is C. len() counts the number of items in a list, not the number of characters in the items. The list ["apple", "banana", "kiwi"] has 3 items, so len() returns 3. len() works the same way on strings (counting characters) and other collections.

Concept Tested: List Length with len()

6. How do you check if "mango" is in the list fruits = ["apple", "banana", "mango"]?

  1. fruits.contains("mango")
  2. fruits.find("mango")
  3. "mango" in fruits
  4. fruits["mango"]
Show Answer

The correct answer is C. The in operator checks membership and returns True or False. "mango" in fruits returns True because "mango" is in the list. You can also use not in to check that something is absent. This works the same way for strings: "py" in "python" returns True.

Concept Tested: Membership with in

7. What is the key difference between mutable and immutable types?

  1. Mutable types are faster; immutable types are slower
  2. Mutable types can be changed after creation; immutable types cannot
  3. Mutable types hold numbers; immutable types hold strings
  4. Mutable types are created with []; immutable types use ()
Show Answer

The correct answer is B. A mutable object can be changed after it is created — you can update, add, or remove items. A list is mutable: colors[0] = "purple" works. An immutable object cannot be changed — you must create a new one instead. Strings are immutable: word[0] = "H" raises a TypeError.

Concept Tested: Mutable vs Immutable

8. What does colors[1] = "purple" do to the list colors = ["red", "green", "blue"]?

  1. Adds "purple" to the end of the list
  2. Creates a brand-new list with "purple" inserted
  3. Replaces "green" (at index 1) with "purple" in the existing list
  4. Raises a TypeError because lists cannot be changed
Show Answer

The correct answer is C. Lists are mutable, so you can assign a new value to any existing index. colors[1] = "purple" changes the item at index 1 from "green" to "purple". After this line, colors is ["red", "purple", "blue"]. This in-place modification is one of the key features that distinguishes lists from immutable types like strings.

Concept Tested: List Indexing

9. Which of the following correctly creates an empty list?

  1. my_list = {}
  2. my_list = None
  3. my_list = ()
  4. my_list = []
Show Answer

The correct answer is D. An empty list is created with [] — square brackets with nothing inside. {} creates an empty dictionary (or set), () creates an empty tuple, and None is a special value meaning "nothing here." You can then add items to the empty list using methods like append().

Concept Tested: List Type

10. What happens when you try to access colors[10] on a list that only has 4 items?

  1. Python returns None for any out-of-range index
  2. Python returns the last item in the list
  3. Python raises an IndexError because the index is out of range
  4. Python automatically extends the list with empty items up to index 10
Show Answer

The correct answer is C. Accessing an index that does not exist in a list raises an IndexError: list index out of range. For a list with 4 items, valid positive indexes are 0, 1, 2, and 3. Trying to access index 10 (or index 4 or higher) causes an error. Always make sure your index is within the valid range.

Concept Tested: List Indexing