PCEP Practice Question: Functions, Tuples, Dictionaries and Exceptions
Which TWO of the following are valid methods that can be called on a tuple object? (Choose two.)
⚠ Common exam trap
The PCEP exam often tests the distinction between mutable and immutable sequence types, trapping candidates who assume that because lists have methods like `.pop()`, `.append()`, and `.sort()`, tuples must have them too, when in fact tuples only support non-mutating methods like `.index()` and `.count()`.
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
✓
.index()
The `.index()` method is a built-in tuple method that returns the index of the first occurrence of a specified value. Tuples are immutable sequences, so they support only non-mutating methods like `.index()` and `.count()`, which do not modify the tuple.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
.pop()
Why it's wrong here
Tuples are immutable, so .pop() cannot exist: it removes and returns an item, mutating the sequence. It tempts because .pop() is a familiar list method, and it would be valid on a list or other mutable sequence, but tuple objects expose only non-mutating methods such as .count() and .index().
- ✓
.index()
Why this is correct
.index() searches a tuple for a specified value and returns the zero-based position of its first occurrence, raising ValueError when absent. Tuples support this read-only lookup because it mutates nothing, satisfying the immutability constraint while providing the membership-position query the question requires.
- ✗
.append()
Why it's wrong here
Tuples are immutable, so .append() cannot exist: it adds an element in place, mutating the sequence. It tempts because .append() is a common list method, and it would be valid on a list, but tuple objects expose only non-mutating methods such as .count() and .index().
- ✗
.sort()
Why it's wrong here
Tuples are immutable, so .sort() cannot exist: it reorders elements in place, mutating the sequence. It tempts because .sort() is a familiar list method, and it would be valid on a list, but tuple objects expose only non-mutating methods such as .count() and .index().
- ✓
.count()
Why this is correct
Tuples implement the sequence protocol, so `.count()` is available: it returns the number of occurrences of a given value within the tuple, satisfying the stem's requirement for a valid tuple method. This read-only query suits tuples' immutability, since counting requires no modification of the underlying object.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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.