PCEP Practice Question: Data Types, Variables, Basic I/O and Operators
Which of the following variable names is valid in Python?
⚠ Common exam trap
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.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
_count
(_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.
Answer analysis
Option-by-option breakdown
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
An identifier cannot begin with a digit, so 1st_value fails to tokenise as a name and raises a SyntaxError. It is tempting because the leading number reads naturally in English, but Python requires the first character to be a letter or underscore.
- ✓
_count
Why this is correct
A leading underscore is a legal identifier character in Python, so `_count` satisfies the naming rules. It is not a keyword, starts with a letter or underscore rather than a digit, and contains no illegal symbols, making it a valid variable name.
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my-var
Why it's wrong here
The hyphen is parsed as the subtraction operator, so my-var is read as my minus var, not a single identifier; only letters, digits and underscores are permitted. It is tempting because hyphens appear in everyday naming conventions, but Python identifiers cannot contain them.
- ✗
class
Why it's wrong here
class is a reserved Python keyword, so assigning to it raises a SyntaxError; keywords cannot serve as identifiers. It is tempting because it reads like an ordinary descriptive word, but the language reserves it for class definitions.
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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.