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 variable names is valid in Python?
1st_value
Why wrong: Invalid: cannot begin with a digit.
_count
Valid: underscores are allowed at the start.
my-var
Why wrong: Invalid: hyphens are not allowed in identifiers.
class
Why wrong: Invalid: 'class' is a reserved keyword.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
_count
Option B (_count) is valid because Python allows identifiers to start with an underscore, and it contains only letters and underscores. Python variable names must start with a letter or underscore, followed by letters, digits, or underscores, and cannot be a reserved keyword.
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.
1st_value
Why it's wrong here
Invalid: cannot begin with a digit.
_count
Why this is correct
Valid: underscores are allowed at the start.
Related concept
Read the scenario before looking for a memorised answer.
my-var
Why it's wrong here
Invalid: hyphens are not allowed in identifiers.
class
Why it's wrong here
Invalid: 'class' is a reserved keyword.
Common exam traps
Python Institute often tests the misconception that underscores are not allowed or that hyphens are acceptable in variable names, leading candidates to reject _count or accept my-var.
Trap categories for this question
Keyword trap
Invalid: 'class' is a reserved keyword.
Detailed technical explanation
Python identifiers are defined by the grammar rule: identifier ::= (letter|'_') (letter | digit | '_')*. This means underscores are treated as letters, making _count valid. The use of leading underscores is a common convention for 'private' or 'internal use' attributes in classes, though Python does not enforce access control. Hyphens are not part of the identifier character set because they conflict with the minus operator, which is why snake_case or camelCase is used instead.
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
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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: _count — Option B (_count) is valid because Python allows identifiers to start with an underscore, and it contains only letters and underscores. Python variable names must start with a letter or underscore, followed by letters, digits, or underscores, and cannot be a reserved keyword.
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.
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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.
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