PCEP Practice Question: Functions, Tuples, Dictionaries and Exceptions

Exhibit

Refer to the exhibit.

data = {'a': 1, 'b': 2, 'c': 3}
for key, value in data.items():
    if value % 2 == 0:
        data.pop(key)
print(data)

What is the output of this code?

⚠ Common exam trap

Python Institute often tests the misconception that deleting keys during iteration will silently skip or partially modify the dictionary, but Python explicitly forbids size changes during iteration to enforce safe iteration contracts.

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

✓

RuntimeError: dictionary changed size during iteration

Modifying a dictionary's size (adding or deleting keys) during iteration over its keys, values, or items raises a RuntimeError. In this code, the loop iterates over the dictionary's keys while deleting them, which changes the dictionary's size and triggers the exception.

Answer analysis

Option-by-option breakdown

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

✓
RuntimeError: dictionary changed size during iteration
Why this is correct
Modifying dict while iterating over its items raises RuntimeError.
✗
{}
Why it's wrong here
Not the output.
✗
{'b': 2}
Why it's wrong here
Not the output.
✗
{'a': 1, 'c': 3}
Why it's wrong here
Modification during iteration raises error.

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PCEP Practice Question: Functions, Tuples, Dictionaries and Exceptions

Exhibit

Why each option matters

Option-by-option breakdown

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