This PCAP practice question tests your understanding of strings. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
Which TWO of the following are immutable in Python?
Set
Why wrong: Sets are mutable.
Tuple
Tuples are immutable.
String
Strings are immutable in Python.
Dictionary
Why wrong: Dictionaries are mutable.
List
Why wrong: Lists are mutable.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
Tuple
Tuple (B) is immutable because once created, its elements cannot be added, removed, or changed. This is enforced by Python's internal structure: tuples are stored as a fixed-length array of PyObject pointers, and any attempt to modify them raises a TypeError.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
Set
Why it's wrong here
Sets are mutable.
Tuple
Why this is correct
Tuples are immutable.
Related concept
Read the scenario before looking for a memorised answer.
String
Why this is correct
Strings are immutable in Python.
Related concept
Read the scenario before looking for a memorised answer.
Dictionary
Why it's wrong here
Dictionaries are mutable.
List
Why it's wrong here
Lists are mutable.
Common exam traps
Python Institute often tests the misconception that strings are mutable because they support indexing and slicing, but candidates forget that any operation that appears to change a string actually returns a new string object, leaving the original unchanged.
Detailed technical explanation
Immutability in Python means the object's state cannot change after creation, which allows tuples and strings to be used as dictionary keys or set members because they are hashable. Under the hood, strings are stored as a contiguous array of Unicode code points (PyUnicodeObject) and any 'modification' creates a new string object, while tuples store references to objects in a fixed C array (PyTupleObject). This immutability also enables Python to intern small strings and reuse them, improving memory efficiency.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
A media company stores terabytes of video archives that are accessed once a year for audit purposes. Moving these objects to a cold storage tier (Azure Archive, S3 Glacier, or Google Nearline) costs a fraction of hot storage. Questions like this test whether you understand storage tiers, access frequency tradeoffs, and retrieval latency requirements.
What to study next
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Strings — study guide chapter
Learn the concepts, then practise the questions
Strings practice questions
Targeted practice on this topic area only
All PCAP questions
511 questions across all exam domains
Certified Associate Python Programmer PCAP study guide
Full concept coverage aligned to exam objectives
PCAP practice test guide
How to use practice tests most effectively before exam day
Related practice questions
Use these pages to review the topic behind this question. This is how one missed question becomes focused revision.
Practise PCAP questions linked to Modules and Packages.
Practise PCAP questions linked to Strings.
Practise PCAP questions linked to Object-Oriented Programming.
Practise PCAP questions linked to Exceptions and File I/O.
Practise PCAP questions linked to PCAP fundamentals.
Practise PCAP questions linked to PCAP scenario.
Practise PCAP questions linked to PCAP troubleshooting.
Practice this exam
Short sessions build daily habit. Longer sessions build exam-day stamina. Try a timed session to simulate real conditions.
FAQ
Strings — This question tests Strings — Read the scenario before looking for a memorised answer..
The correct answer is: Tuple — Tuple (B) is immutable because once created, its elements cannot be added, removed, or changed. This is enforced by Python's internal structure: tuples are stored as a fixed-length array of PyObject pointers, and any attempt to modify them raises a TypeError.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Read the scenario before looking for a memorised answer.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
Last reviewed: Jun 30, 2026
This PCAP practice question is part of Courseiva's free Python Institute certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the PCAP exam.
Question Discussion
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
Sign in to join the discussion.