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.
>>> s = "Hello" >>> s[1] = "a"
Refer to the exhibit. What happens when the code is executed?
>>> s = "Hello" >>> s[1] = "a"
The string becomes "Hallo"
Why wrong: Strings are immutable, so item assignment is not allowed.
A TypeError is raised
Strings are immutable; assigning to an index raises TypeError.
A SyntaxError is raised
Why wrong: The syntax is valid; the error occurs at runtime.
The code runs without error and s remains "Hello"
Why wrong: Assignment to a string index raises a TypeError.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
A TypeError is raised
The code attempts to modify a string by assigning a new character to an index position (s[0] = 'H'). Strings in Python are immutable, meaning their elements cannot be changed after creation. This operation raises a TypeError because the item assignment is not supported for string objects.
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.
The string becomes "Hallo"
Why it's wrong here
Strings are immutable, so item assignment is not allowed.
A TypeError is raised
Why this is correct
Strings are immutable; assigning to an index raises TypeError.
Related concept
Read the scenario before looking for a memorised answer.
A SyntaxError is raised
Why it's wrong here
The syntax is valid; the error occurs at runtime.
The code runs without error and s remains "Hello"
Why it's wrong here
Assignment to a string index raises a TypeError.
Common exam traps
Python Institute often tests the immutability of strings by presenting code that attempts index assignment, trapping candidates who assume strings are mutable like lists.
Detailed technical explanation
Under the hood, Python strings are stored as immutable sequences of Unicode code points. When you attempt to assign to an index, Python's type system checks for a __setitem__ method, which strings do not implement, leading to a TypeError. This immutability allows strings to be used as dictionary keys and enables optimizations like interning. In real-world scenarios, to modify a string, you must create a new one using slicing or the replace() method.
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
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FAQ
Strings — This question tests Strings — Read the scenario before looking for a memorised answer..
The correct answer is: A TypeError is raised — The code attempts to modify a string by assigning a new character to an index position (s[0] = 'H'). Strings in Python are immutable, meaning their elements cannot be changed after creation. This operation raises a TypeError because the item assignment is not supported for string objects.
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 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.
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