This PCEP practice question tests your understanding of data types, variables, basic i/o and operators. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. 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.
A function sometimes returns None. Which expression correctly checks if the return value is not None?
if not val is None:
Why wrong: Works but less readable.
if val != None:
Why wrong: Works but not idiomatic; PEP 8 recommends 'is not'.
if val is not None:
Correct and idiomatic.
if val:
Why wrong: False if val is None, also false for 0, empty string, etc.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
if val is not None:
Option C is correct because the `is not` operator is the proper way to check identity inequality in Python. Since `None` is a singleton, comparing with `is not` ensures you are checking whether the value is literally the `None` object, which is the recommended and most readable approach for `None` checks.
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.
if not val is None:
Why it's wrong here
Works but less readable.
if val != None:
Why it's wrong here
Works but not idiomatic; PEP 8 recommends 'is not'.
if val is not None:
Why this is correct
Correct and idiomatic.
Related concept
Read the scenario before looking for a memorised answer.
if val:
Why it's wrong here
False if val is None, also false for 0, empty string, etc.
Common exam traps
Python Institute often tests the distinction between identity (`is`) and equality (`==`) operators, and the trap here is that candidates mistakenly use `!= None` (value comparison) instead of `is not None` (identity comparison), or confuse truthiness checks with `None` checks.
Detailed technical explanation
In Python, `None` is a singleton object of type `NoneType`, and the `is` operator compares object identity (memory address) rather than value equality. Using `is not None` is the PEP 8 recommended style because it explicitly checks for the singleton `None` and avoids potential issues with custom `__eq__` methods that might make `== None` return unexpected results. This distinction is critical in contexts like function return values where `None` indicates absence of a result, such as when a function explicitly returns `None` or falls off the end without a return statement.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
A practitioner preparing for the PCEP exam encounters this exact type of scenario on the job. The correct answer here is not the most general option — it is the best answer for the specific constraint described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Real exam questions reward reading the full scenario before eliminating options, because the constraint defines which answer fits.
What to study next
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Data Types, Variables, Basic I/O and Operators — study guide chapter
Learn the concepts, then practise the questions
Data Types, Variables, Basic I/O and Operators practice questions
Targeted practice on this topic area only
All PCEP questions
510 questions across all exam domains
Certified Entry-Level Python Programmer PCEP study guide
Full concept coverage aligned to exam objectives
PCEP 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 PCEP questions linked to Computer Programming and Python Fundamentals.
Practise PCEP questions linked to Data Types, Variables, Basic I/O and Operators.
Practise PCEP questions linked to Control Flow, Loops, Lists and Logic.
Practise PCEP questions linked to Functions, Tuples, Dictionaries and Exceptions.
Practise PCEP questions linked to PCEP fundamentals.
Practise PCEP questions linked to PCEP scenario.
Practise PCEP questions linked to PCEP troubleshooting.
Practice this exam
Short sessions build daily habit. Longer sessions build exam-day stamina. Try a timed session to simulate real conditions.
FAQ
Data Types, Variables, Basic I/O and Operators — This question tests Data Types, Variables, Basic I/O and Operators — Read the scenario before looking for a memorised answer..
The correct answer is: if val is not None: — Option C is correct because the `is not` operator is the proper way to check identity inequality in Python. Since `None` is a singleton, comparing with `is not` ensures you are checking whether the value is literally the `None` object, which is the recommended and most readable approach for `None` checks.
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 →
Keep practising
Last reviewed: Jun 30, 2026
This PCEP 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 PCEP 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.