PCEP Practice Question: Functions, Tuples, Dictionaries and Exceptions

What happens when you try to modify a tuple?

t = (1, 2, 3) t[0] = 0

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

✓

A TypeError is raised

Tuples are immutable, so trying to assign to an index raises a TypeError.

Answer analysis

For each option: why learners choose it and why it is or isn't the right answer here.

✓
A TypeError is raised
Why this is correct
Tuples are immutable, so item assignment such as t[0] = 0 is unsupported. Python raises a TypeError at runtime rather than silently ignoring the change, which is the defined behaviour for attempting to modify tuple elements.
✗
A IndexError is raised
Why it's wrong here
Assigning to a tuple index raises TypeError, not IndexError, because index 0 exists and is valid. IndexError arises only when the index is out of range. It tempts because both errors concern indexing, but the failure here is the immutability of the tuple, not a missing element.
✗
The tuple becomes (0, 2, 3)
Why it's wrong here
The tuple cannot become (0, 2, 3); immutability means no item assignment is permitted, so a TypeError is raised and the original tuple is unchanged. It tempts because lists behave exactly this way, and the syntax looks identical, but tuples lack the mutation support lists provide.
✗
The code runs without error
Why it's wrong here
Tuples are immutable, so item assignment raises TypeError before any change occurs. The code cannot run without error. It tempts because tuples support indexing for reads, so learners assume writes behave the same way; the immutability constraint blocks assignment to an existing index.

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