PCEP Functions, Tuples, Dictionaries and Exceptions Practice Test 5 — 15 Questions

Question 1

A developer writes a function that takes a tuple as an argument and tries to modify an element inside the tuple. What happens?

Accepted Answer

The code raises a TypeError.. Tuples in Python are immutable, meaning their elements cannot be changed after creation. Attempting to modify an element (e.g., `my_tuple[0] = 5`) raises a `TypeError` because the tuple object does not support item assignment. This is a fundamental property of the tuple data type.

Answer

The tuple is converted to a list automatically.

Answer

The first element is modified successfully.

Answer

The code raises a ValueError.

Question 2

Which TWO of the following statements about tuples in Python are true?

Accepted Answer

Tuples can be used as dictionary keys if all elements are hashable.. Option B is correct because a tuple is hashable only when every element it contains is hashable, so a tuple such as (1, 'a') can serve as a dictionary key, while one containing a list cannot. Option E is correct because tuples are immutable sequences: once created, their length and element references cannot be changed, though they support indexing, slicing, concatenation, and repetition. Option A is wrong because tuples containing mutable or unhashable elements, such as ([1, 2],), are not hashable. Option C is wrong because tuples fully support indexing and slicing, e.g., t[0]. Option D is wrong because tuples may contain mutable objects like lists; the tuple itself is immutable, but its elements need not be.

Answer

Tuples are always hashable.

Answer

Tuples do not support indexing.

Answer

Tuples can only contain immutable objects.

Question 3

Order the steps to create and use a list in Python.

Accepted Answer

1. Create a list with brackets: my_list = []
2. Assign it to a variable: my_list = [1, 2, 3]
3. Access elements by index: print(my_list[0])
4. Modify elements by assignment: my_list[0] = 10
5. Grow the list with methods: my_list.append(4). Lists are created with brackets, assigned to variables, accessed by index, modified by assignment, and grown with methods.

Answer

1. Access elements by index: my_list[0]
2. Create a list with brackets: []
3. Assign it to a variable: my_list = []
4. Modify elements by assignment: my_list[0] = 10
5. Grow the list with methods: my_list.append(4)

Answer

1. Create a list with brackets: my_list = []
2. Access elements by index: print(my_list[0])
3. Assign it to a variable: my_list = [1, 2, 3]
4. Modify elements by assignment: my_list[0] = 10
5. Grow the list with methods: my_list.append(4)

Answer

1. Create a list with brackets: my_list = []
2. Assign it to a variable: my_list = [1, 2, 3]
3. Grow the list with methods: my_list.append(4)
4. Access elements by index: print(my_list[0])
5. Modify elements by assignment: my_list[0] = 10

Question 4

Order the steps to define a class and create an object in Python.

Accepted Answer

Define the class with the `class` keyword and include the `__init__` method, then create an instance by calling the class name, then use the object by calling its methods or accessing attributes.. In Python, to define a class and create an object, you must first write a class definition using the `class` keyword, which typically includes the `__init__` method (the constructor) to initialize attributes. After that, you instantiate the class by calling it like a function, optionally passing arguments to `__init__`. Finally, you use the resulting object by accessing its attributes or calling its methods. Any deviation from this order, such as instantiating before defining the class or omitting the constructor, will lead to errors because the class must exist and be properly defined before any objects can be created.

Answer

Create an instance by calling the class name, then define the class, then use the object.

Answer

Define the class without the `__init__` method, then create an instance, then add the `__init__` method later.

Answer

Define the class, then use the class directly without creating an instance.

Question 5

Which of the following correctly creates a tuple with a single element 5?

Accepted Answer

t = (5,). In Python, a tuple with a single element requires a trailing comma after the element. Without the comma, parentheses are treated as grouping operators for expression evaluation, not as a tuple literal. Thus, `t = (5,)` creates a tuple containing the integer 5.

Answer

t = (5)

Answer

t = (5)

Answer

t = (5, 5)

Question 6

A programmer needs to store configuration settings keyed by string, where each key maps to a list of allowed values. Which data structure is most appropriate?

Accepted Answer

A dictionary where keys are strings and values are lists.. A dictionary in Python provides direct key-to-value mapping, making it ideal for storing configuration settings where each string key must map to a list of allowed values. Dictionaries offer O(1) average-time complexity for lookups, which is efficient for retrieving the list of values for a given key. This structure directly models the requirement without unnecessary nesting or indirection.

Answer

A tuple of lists where each list starts with the key.

Answer

A list of tuples where each tuple contains a key and a list of values.

Answer

A set of strings representing the keys, with a separate list for values.

Question 7

Consider the following code:

def foo(x, y):
    return x * y

result = foo(y=2, 3)

What is the error?

Accepted Answer

A positional argument follows a keyword argument.. In Python, when calling a function, all positional arguments must appear before any keyword arguments. The call `foo(y=2, 3)` violates this rule by placing a positional argument (`3`) after a keyword argument (`y=2`), which raises a SyntaxError. This is enforced by Python's parser to avoid ambiguity in argument binding.

Answer

The function requires at least one argument but none provided.

Answer

Keyword arguments cannot be used in function calls.

Answer

The function definition has too many parameters.

Question 8

Which exception is raised when trying to access a dictionary key that does not exist?

Accepted Answer

KeyError. In Python, when you attempt to access a dictionary key that does not exist using square bracket notation (e.g., `my_dict['nonexistent']`), the interpreter raises a `KeyError`. This is the standard exception for missing dictionary keys, as defined in the Python language specification. The correct answer is A.

Answer

TypeError

Answer

ValueError

Answer

AttributeError

Question 9

A developer is using a lambda function that takes two arguments and returns their sum. Which of the following lambda expressions is correct?

Accepted Answer

lambda a, b: a + b. Option A correctly defines a lambda function that takes two arguments and returns their sum. Option B is a valid lambda but returns the difference (a - b), not the sum, so it does not meet the requirement. Option C is incorrect because lambda expressions cannot include a `return` statement; the result is implicitly returned. Option D uses `def` to define a named function, not a lambda.

Answer

lambda a, b: a - b

Answer

lambda a, b: return a + b

Answer

def add(a, b): return a + b

Question 10

What does the following code output?

try:
    x = int('abc')
except ValueError:
    print('Invalid')

Accepted Answer

Invalid. The code attempts to convert the string 'abc' to an integer using int(). Since 'abc' is not a valid integer, Python raises a ValueError. The except block catches this specific exception and executes print('Invalid'), so the output is 'Invalid'. Option B is correct because the exception is handled gracefully without crashing.

Answer

The program crashes

Answer

(Nothing printed)

Answer

abc

Question 11

Given the tuple t = (1, 2, 3, 4, 5), which expression returns the last element?

Accepted Answer

t[-1]. In Python, negative indices count from the end of a sequence. For the tuple t = (1, 2, 3, 4, 5), t[-1] accesses the last element (5), because -1 refers to the final position. This is a standard feature of Python's sequence indexing.

Answer

t[5]

Answer

t[4]

Answer

t[0]

Question 12

Which of the following will raise a TypeError?

Accepted Answer

t = (1, 2); t[0] = 3. Tuples are immutable in Python; attempting to assign a value to an element using indexing (e.g., `t[0] = 3`) raises a `TypeError` with the message 'tuple' object does not support item assignment. This is a fundamental property of the tuple data type, designed to create fixed sequences that cannot be changed after creation.

Answer

lst = [1, 2]; lst.extend([3, 4])

Answer

x = {1, 2} & {2, 3}

Answer

d = {'a': 1}; d['b'] = 2

Question 13

Which TWO of the following are valid ways to create a dictionary with initial key-value pairs? (Select exactly 2)

Accepted Answer

d = {'a': 1, 'b': 2}. It uses the standard literal syntax for creating a dictionary with initial key-value pairs. The curly braces `{}` with colon-separated keys and values are the most common and direct way to define a dictionary in Python.

Answer

d = ('a'=1, 'b'=2)

Answer

d = dict.fromkeys(['a', 'b', 'c']) # without value

Answer

d = dict(['a', 'b'], [1, 2])

Question 14

Which of the following statements about function arguments are true? (Select all that apply)

Accepted Answer

Keyword arguments can be passed in any order, regardless of their position in the function definition.. The correct statements are A, B, D, and E. Keyword arguments can be passed in any order because they are matched by name (A). The **kwargs parameter collects additional keyword arguments into a dictionary (B). The *args parameter collects additional positional arguments into a tuple (D). Default arguments are evaluated once at function definition time (E). Option C is incorrect because *args must always appear before **kwargs in a function definition.

Answer

The *args parameter must always come after **kwargs in a function definition.

Question 15

Which TWO of the following exceptions are built-in Python exceptions? (Select exactly 2)

Accepted Answer

ZeroDivisionError. ZeroDivisionError is a built-in Python exception that is raised when the second operand of a division or modulo operation is zero. It is part of Python's standard exception hierarchy and is commonly encountered in arithmetic operations.

Answer

StringError

Answer

NumberError

Answer

ListError