Match each exception to its cause.
Drag a concept onto its matching description — or click a concept then click the description.
Operation on incompatible type
Function receives argument with correct type but invalid value
Sequence subscript out of range
Mapping key not found
Attribute reference or assignment fails
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
ValueError: Raised when a built-in operation or function receives an argument that has the right type but an inappropriate value.
Correct matches: ValueError with inappropriate value, TypeError with wrong type, IndexError with out-of-range index, KeyError with missing key. Common confusions arise from swapping the definitions of ValueError and TypeError, or TypeError and KeyError.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
ValueError: Raised when a built-in operation or function receives an argument that has the right type but an inappropriate value.
Why this is correct
ValueError is raised when a built-in operation or function accepts an argument whose type is valid, but the actual value is unacceptable because it violates the operation's constraints or domain. For example, int('abc') passes the correct type (str) but the string does not represent a valid integer, so Python raises ValueError. This distinguishes value errors from type errors.
TypeError: Raised when an operation or function is applied to an object of inappropriate type.
Why this is correct
TypeError occurs when a function or operation is applied to an object whose type is fundamentally incompatible with the expected operand. For instance, adding a string to an integer, such as 'abc' + 1, raises TypeError because the '+' operator lacks a valid definition for that combination of types. Similarly, len(5) fails because integers do not support the length protocol. This exception signals a type mismatch, not a problem with an otherwise valid value.
IndexError: Raised when a sequence subscript is out of range.
Why this is correct
IndexError is raised when a subscript expression retrieves an element from a sequence, such as a list, tuple, or string, using an index that falls outside the valid range of existing positions. For a sequence of length n, valid indices are 0 through n-1 (or negative indices from -1 to -n); trying to access index n or -n-1 triggers IndexError. It specifically applies to sequential containers, not to mappings, where a missing key would instead raise KeyError.
KeyError: Raised when a mapping key is not found in the set of existing keys.
Why this is correct
KeyError is raised when a mapping type, like a dictionary, is accessed with a key that does not exist in its set of keys. Unlike sequences, dictionaries are not indexed by position; they are accessed by arbitrary hashable keys, and querying an absent key, for example d['missing'], causes KeyError. This distinguishes mapping lookups from sequence subscripting, which would raise IndexError when out of range.
ValueError: Raised when an operation or function is applied to an object of inappropriate type.
Why it's wrong here
This statement is incorrect because the described cause—applying an operation to an object of inappropriate type—is the precise definition of TypeError, not ValueError. ValueError is reserved for cases where the argument's type is acceptable but its value is invalid, such as a number outside a function's domain. Therefore, matching this cause to ValueError confuses two distinct exception classes with different triggering conditions.
TypeError: Raised when a mapping key is not found in the set of existing keys.
Why it's wrong here
This statement is incorrect because the cause given—a mapping key not being found in the existing set of keys—is exactly the condition that raises KeyError, not TypeError. TypeError deals with operations on objects of the wrong type or incompatible operand types, such as attempting to concatenate a string and an integer. A missing key is unrelated to type mismatches; it occurs even when the key's type is perfectly appropriate for the mapping. Thus, this pairing misattributes a key-existence error to the wrong exception.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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.