PCEP Practice Exam 2 — 20 Questions

Question 1

In a try-except block, a developer has two except clauses: except ValueError: and except: (bare except). If the code in the try block raises a ValueError, which except clause is executed?

Accepted Answer

The ValueError except clause. When a ValueError is raised in the try block, Python searches the except clauses in the order they appear. It finds the first matching clause, which is `except ValueError:`, and executes it. The bare `except:` clause is only reached if no preceding named except clause matches the exception type.

Answer

Both in order

Answer

Neither; program crashes

Answer

The bare except clause

Question 2

A programmer needs to swap the values of two variables a and b without using a temporary variable. Which approach works in Python?

Accepted Answer

a, b = b, a. Python supports tuple unpacking, which allows the values of a and b to be swapped in a single atomic operation: a, b = b, a. This works by creating a tuple (b, a) on the right-hand side, then unpacking it into the variables on the left, effectively swapping the values without a temporary variable.

Answer

a = b; b = a

Answer

a = a ^ b; b = a ^ b; a = a ^ b

Answer

a = b + a; b = a - b; a = a - b

Question 3

Which three of the following statements about lists are true? (Choose three.)

Accepted Answer

Lists can be indexed with integers.. Lists in Python are ordered sequences that support indexing with integers, starting from 0 for the first element and negative integers for reverse indexing. This allows direct access to any element by its position, a fundamental feature of sequence types in Python.

Answer

Lists have a fixed size once created.

Answer

Lists can only contain elements of the same data type.

Question 4

What is the output of: print(2 ** 3 ** 2)?

Accepted Answer

512. In Python, the exponentiation operator ** is right-associative, meaning that `2 ** 3 ** 2` is evaluated as `2 ** (3 ** 2)`, not `(2 ** 3) ** 2`. First, `3 ** 2` equals 9, then `2 ** 9` equals 512. Thus, the correct output is 512.

Answer

12

Answer

64

Answer

256

Question 5

A developer wants to raise a ValueError with a custom message when a negative number is passed. Which code is correct?

Accepted Answer

raise ValueError("Negative input not allowed"). In Python, raising an exception with a custom message requires passing the message as an argument to the exception constructor: `raise ValueError("Negative input not allowed")`. This creates a ValueError instance with the specified message, which is the standard and only syntactically valid way to include a custom message in a raise statement.

Answer

raise ValueError "Negative input not allowed"

Answer

raise ValueError() + "Negative input not allowed"

Answer

raise new ValueError("Negative input not allowed")

Question 6

Which THREE of the following are valid ways to create a list in Python?

Accepted Answer

list((1, 2, 3)). Option A, list((1, 2, 3)), is correct because the list() constructor accepts any iterable — here a tuple — and returns a new list object [1, 2, 3]. Option B, [x for x in range(3)], is correct because a list comprehension is a valid literal-style expression that builds a list, producing [0, 1, 2]. Option C, [1, 2, 3], is correct because it is a direct list display (literal) using square brackets, which is the most basic way to create a list. Option D, (1, 2, 3), is not correct because parentheses with commas create a tuple, not a list. Option E, {1, 2, 3}, is not correct because curly braces create a set (or a dict if key-value pairs are used), not a list.

Answer

(1, 2, 3)

Answer

{1, 2, 3}

Question 7

Which of the following is NOT a valid variable name in Python?

Accepted Answer

2nd_var. Python variable names cannot start with a digit. The name '2nd_var' begins with '2', which violates Python's identifier naming rules. Valid variable names must start with a letter (a-z, A-Z) or an underscore (_), and can be followed by letters, digits, or underscores.

Answer

_myvar

Answer

myVar2

Answer

my_var

Question 8

Refer to the exhibit. What is the printed value?

Accepted Answer

35. The expression in the exhibit is (2+3)*(5+2). Parentheses have the highest precedence, so we first evaluate the two addition operations: 2+3=5 and 5+2=7. Then we multiply the results: 5*7=35. Therefore, the printed value is 35, corresponding to option D.

Answer

27

Answer

5

Answer

21

Question 9

Match each Python keyword to its use.

Accepted Answer

break: Exits the innermost loop. The correct matches are: break is used to exit a loop prematurely; continue skips the current iteration; pass is a no-operation statement. Common mistakes include swapping the definitions of break and continue.

Answer

break: Skips the rest of the current iteration

Answer

continue: Exits the innermost loop

Question 10

A Python program prompts the user for their age and stores it in a variable. Which is the correct way to convert the input to an integer?

Accepted Answer

age = int(input("Age: ")). The `input()` function in Python always returns a string, and to perform arithmetic operations or numeric comparisons, the string must be explicitly converted to an integer using the `int()` constructor. This is a fundamental requirement for type conversion in Python when handling user input.

Answer

age = str(input("Age: "))

Answer

age = float(input("Age: "))

Answer

age = input("Age: ")

Question 11

A programmer needs to store a fixed set of error codes that should not change during program execution. Which data type is most appropriate for this purpose?

Accepted Answer

tuple. A tuple is an immutable sequence, so its contents cannot be altered after creation. This ensures that the set of error codes remains constant throughout the program's execution. While lists, dictionaries, and sets can hold multiple values, they are all mutable, meaning they could be accidentally modified. The immutability of tuples makes them the most appropriate choice for storing fixed data.

Answer

dictionary

Answer

set

Answer

list

Question 12

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 13

A developer defines a function and calls it as shown:

def greet(name, greeting='Hello'):
    return greeting + ', ' + name

print(greet('Ana'))

What is printed?

Accepted Answer

Hello, Ana. Default parameter values let a caller omit arguments that have sensible fallbacks. Because greet is invoked with only 'Ana', that value binds to name while greeting uses its default 'Hello'. The concatenation then yields the string 'Hello, Ana', which is printed to the console.

Answer

A TypeError is raised.

Answer

Hello, greeting

Answer

Ana, Hello

Question 14

Match each Python data type to its description.

Accepted Answer

int: Whole numbers. The correct matches are: A (int - whole numbers), B (float - numbers with decimal point), D (bool - Boolean values True or False). Option C (str) is incorrect because strings are immutable sequences of characters, not mutable collections. Option E (list) is incorrect because lists are mutable collections, not immutable sequences. Option F (tuple) is incorrect because tuples are immutable sequences, not mutable collections.

Answer

str: Ordered, mutable collection of items

Answer

list: Immutable sequence of characters

Answer

tuple: Ordered, mutable collection of items

Question 15

A developer writes a function to log sensor readings. The function is defined as:

def log_reading(sensor_id, value, unit="C"):
    return f"{sensor_id}: {value}{unit}"

The developer calls log_reading("T1", 22, unit="F"). What is the result?

Accepted Answer

"T1: 22F". The function call provides two positional arguments ("T1" and 22) and one keyword argument (unit="F"). The keyword argument overrides the default value "C". The f-string then interpolates sensor_id, value, and unit, producing "T1: 22F". This demonstrates how default parameters can be overridden by explicit keyword arguments in a function call.

Answer

A SyntaxError because keyword arguments must come before positional arguments.

Answer

A TypeError because the function expects three arguments and only two positional arguments were given.

Answer

"T1: 22C"

Question 16

Which THREE statements about the break statement in Python are correct? (Choose three.)

Accepted Answer

It exits the innermost loop when executed.. The break statement, when executed inside a loop, immediately terminates the innermost loop it resides in, transferring control to the next statement after the loop. This is a fundamental behavior defined in Python's control flow documentation.

Answer

It can be used with an optional else clause.

Answer

It can be used in an if statement outside any loop.

Question 17

Which TWO of the following code snippets will produce the output '0 1 2'? (Choose two.)

Accepted Answer

for i in range(5): if i>2: break; print(i). The loop iterates over range(5) (0,1,2,3,4), but the break statement executes when i > 2, so the loop terminates after printing 0, 1, and 2. Option D is correct because range(3) generates exactly the sequence 0, 1, 2, and each value is printed in order.

Answer

for i in range(5): if i%2==0: print(i); else: continue

Answer

i=0; while i<3: print(i); i+=1; else: print('done')

Answer

i=0; while i<3: print(i)

Question 18

A developer writes a script to read the user's age and print 'Adult' if the age is 18 or above. The code outputs 'Adult' for age 9. What is the most likely cause?

Accepted Answer

The input was not converted to integer.. The most likely cause is that the input was not converted to integer. In Python, the `input()` function returns a string. When comparing strings lexicographically, '9' >= '18' evaluates to True because '9' is greater than '1' in the first character. Thus, the condition `age >= '18'` (or similar) would mistakenly output 'Adult' for age 9. Converting the input to an integer with `int()` ensures numeric comparison, where 9 >= 18 is False.

Answer

The if statement lacked parentheses around the condition.

Answer

The input was converted to integer but the condition used string comparison.

Answer

The condition used >= instead of >.

Question 19

Which TWO of the following Python data types are mutable?

Accepted Answer

list. Option A (list) is correct because Python lists are mutable sequence types: you can change, add, or remove elements in place (e.g., append(), item assignment) without creating a new object. Option E (dict) is correct because dictionaries are mutable mappings: key-value pairs can be added, updated, or deleted in place (e.g., d['k'] = v, del d['k']). The unmarked options are immutable: str (B) cannot be modified in place since strings are immutable sequences, tuple (C) is an immutable sequence whose contents cannot be reassigned, and int (D) is an immutable numeric type where any arithmetic produces a new object rather than modifying the original.

Answer

str

Answer

tuple

Answer

int

Question 20

A junior developer is writing a script to calculate the total cost of items in a shopping cart. The script uses variables item_price (float) and quantity (int). The code is:

item_price = 2.5
quantity = 3
total = item_price * quantity
print("Total: " + total)

When run, this code raises a TypeError. The developer is confused because the multiplication seems correct. What is the most likely issue and the correct fix?

Accepted Answer

The print function cannot concatenate a string with a float; convert total to string using str(total).. The `print` function in Python expects all arguments to be strings when using the `+` operator for concatenation. The variable `total` is a float (result of multiplying a float by an int), and Python does not implicitly convert it to a string. The error is a `TypeError: can only concatenate str (not 'float') to str`. The fix is to explicitly convert `total` to a string using `str(total)` before concatenation.

Answer

The variable total is being overwritten by the print statement; use a different variable name.

Answer

The multiplication should be written as int(item_price) * quantity to ensure integer result.

Answer

The variable names are too descriptive; rename them to a and b to avoid confusion.