This PCEP practice question tests your understanding of data types, variables, basic i/o and operators. 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 of the following is NOT a valid variable name in Python?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "NOT"
Why it matters: Negative qualifier — you are looking for the one option that does NOT apply. Most options will be true; only one is false for this scenario.
_myvar
Why wrong: Valid; names can start with underscore.
myVar2
Why wrong: Valid; letters and digits are allowed after first character.
2nd_var
Invalid; names cannot start with a digit.
my_var
Why wrong: Valid; underscores are allowed.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
2nd_var
Option C is correct because Python variable names cannot start with a digit. The name '2nd_var' begins with '2', which violates Python's identifier naming rules. Valid variable names must start with a letter (a-z, A-Z) or an underscore (_), and can be followed by letters, digits, or underscores.
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.
_myvar
Why it's wrong here
Valid; names can start with underscore.
myVar2
Why it's wrong here
Valid; letters and digits are allowed after first character.
2nd_var
Why this is correct
Invalid; names cannot start with a digit.
Clue confirmation
The clue word "NOT" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
my_var
Why it's wrong here
Valid; underscores are allowed.
Common exam traps
Cisco often tests the rule that variable names cannot start with a digit, knowing that candidates may mistakenly think digits are allowed anywhere or that underscores are not valid starting characters.
Detailed technical explanation
Python's identifier rules follow the Unicode standard for identifiers (PEP 3131), allowing letters from many alphabets, but digits are still prohibited as the first character. This rule prevents ambiguity in parsing, as a leading digit would make the token indistinguishable from a numeric literal. In practice, this means variable names like '1st_place' are invalid, while '_1st_place' is valid.
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: 2nd_var — Option C is correct because Python variable names cannot start with a digit. The name '2nd_var' begins with '2', which violates Python's identifier naming rules. Valid variable names must start with a letter (a-z, A-Z) or an underscore (_), and can be followed by letters, digits, or underscores.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Yes — watch for: "NOT". Negative qualifier — you are looking for the one option that does NOT apply. Most options will be true; only one is false for this scenario.
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 25, 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.