PCEP Timed Practice Test 3 — 10 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: ")