200-901 Software Development and Design Practice Question
Which Python data type is mutable and unordered?
⚠ Common exam trap
Cisco often tests the distinction between mutable vs. immutable and ordered vs. unordered, and the trap here is that candidates confuse the ordered nature of lists (mutable, ordered) with the unordered nature of dictionaries, or mistakenly think tuples are mutable because they can contain mutable objects.
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
✓
Dictionary
Options C (Dictionary) and D (Set) are both correct because dictionaries and sets are mutable and unordered. Dictionaries store key-value pairs and sets store unique elements, both allowing addition/removal without guaranteed order (prior to Python 3.7 for dicts, and always for sets). Lists (A) are mutable but ordered, and tuples (B) are immutable and ordered, making them incorrect.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
List
Why it's wrong here
Incorrect. Lists are mutable but ordered (maintain insertion order).
- ✗
Tuple
Why it's wrong here
Incorrect. Tuples are immutable and ordered.
- ✓
Dictionary
Why this is correct
Correct. Dictionaries are mutable and unordered (accessed by key, not index).
- ✓
Set
Why this is correct
Correct. Sets are mutable and unordered (no indexing, no duplicate elements).
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Written by Johnson Ajibi, MSc IT Security
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