PCEP Computer Programming and Python Fundamentals Practice Test 1 — 15 Questions

Question 1

A developer writes a script that prompts the user for their age and stores it in a variable. Which code snippet correctly converts the input to an integer?

Accepted Answer

age = int(input("Enter age: ")). It uses the `int()` function to convert the string returned by `input()` into an integer. The `input()` function always returns a string, so wrapping it with `int()` performs the type conversion needed for numeric operations.

Answer

age = int(input)

Answer

age = input("Enter age: ", int)

Answer

age = input(int("Enter age: "))

Question 2

Given the code: a = [1, 2, 3]; b = a; b.append(4). What is the value of a?

Accepted Answer

[1, 2, 3, 4]. In Python, variables hold references to objects, not copies. When `b = a` is executed, both `a` and `b` point to the same list object in memory. The `append()` method modifies the list in-place, so the change is visible through both references. Thus, `a` becomes `[1, 2, 3, 4]`.

Answer

Error

Answer

[1, 2, 3]

Answer

[1, 2, 3, [4]]

Question 3

A student writes the code: x = 10; if x > 5: print("big"); else: print("small"). What is the output?

Accepted Answer

big. The code `x = 10; if x > 5: print("big"); else: print("small")` is syntactically correct in Python. Since `x` is 10, the condition `x > 5` evaluates to `True`, so the `if` branch executes, printing `"big"`. The semicolons are allowed as statement separators, and the colon after `if` and `else` is required. Therefore, option D is correct.

Answer

small

Answer

SyntaxError

Answer

big
small

Question 4

Which TWO of the following code snippets will result in a SyntaxError? (Choose two.)

Accepted Answer

if x > 5
    print('big'). Causes a SyntaxError because the `if` statement is missing a colon (`:`) after the condition, which is required for compound statements. Options A, B, C, and E are all valid Python 3 syntax. Option A uses multiple statements on one line with a semicolon. Option B calls the `print()` function correctly. Option C correctly uses a colon and indentation for the `for` loop. Option E correctly uses a colon for the `if` statement. Therefore, only D is a SyntaxError.

Answer

a = 1; b = 2

Answer

print('hello')

Answer

for i in range(5):
    print(i)

Answer

if x > 5:
    print('big')

Question 5

A system administrator is writing a Python script to monitor disk usage. The script uses the psutil library (not part of PCEP scope, but the scenario is generic). The administrator writes:

import psutil
disk = psutil.disk_usage('/')
print(disk.free)

But the script fails with an ImportError because psutil is not installed. The administrator decides to handle this gracefully: if the module is missing, the script should print a custom error message and exit without crashing. Which code snippet achieves this?

Accepted Answer

try:
    import psutil
except ImportError:
    print('psutil not installed. Please install.')
    sys.exit(1). It uses a try-except block to catch the ImportError specifically when the import statement fails. This allows the script to print a custom error message and then call sys.exit(1) to terminate gracefully with a non-zero exit code, which is the standard way to signal failure in a script. The other options either do not handle the missing module correctly or fail to exit the script properly.

Answer

import psutil
if not psutil:
    print('psutil not installed.')
    sys.exit(1)

Answer

try:
    import psutil
except ImportError:
    print('psutil not installed. Please install.')

Answer

try:
    import psutil
except:
    print('Module missing.')
    raise

Question 6

A developer writes a Python script that calculates the average of a list of numbers. The script sometimes produces a ZeroDivisionError. Which of the following is the MOST appropriate way to handle this error to keep the script running?

Accepted Answer

Wrap the division in a try/except block and catch ZeroDivisionError, then set the average to 0.. It uses a try/except block to catch the ZeroDivisionError specifically, which is the most robust and Pythonic way to handle runtime errors. This approach keeps the script running by setting the average to 0 when the list is empty, without relying on pre-checks that might miss other causes of division by zero (e.g., if the sum is 0 but the list is not empty). In Python, exception handling is preferred for error-prone operations like division, as it separates normal logic from error handling cleanly.

Answer

Check if len(numbers) == 0 before division and skip calculation if true.

Answer

Use an if statement to check if the list is empty and print a warning message.

Answer

Remove the last element from the list if it is empty.

Question 7

A Python script contains the following line: x = 5. Later in the script, the programmer wants to check if x is an integer. Which of the following is the BEST way to perform this check?

Accepted Answer

if isinstance(x, int):. `isinstance(x, int)` is the recommended way to check if a variable is an instance of a specific class in Python. It handles inheritance correctly (e.g., if `x` were a subclass of `int`) and is more robust than directly comparing types with `type()`. This aligns with Python's duck typing philosophy and is the standard approach in professional code.

Answer

if x is integer:

Answer

if x == 'integer':

Answer

if type(x) == int:

Question 8

Which TWO of the following are valid Python variable names? (Choose two.)

Accepted Answer

var123. (var123) is correct because Python variable names must start with a letter or underscore, and can contain letters, digits, or underscores. 'var123' starts with a letter and contains only valid characters, making it a legal identifier.

Answer

for

Answer

my-var

Answer

1var

Question 9

What is the output of the code in the exhibit?

Accepted Answer

TypeError. The code attempts to concatenate a string ('10') and an integer (5) using the + operator. In Python, the + operator does not implicitly convert types; it raises a TypeError because it cannot determine whether to perform string concatenation or integer addition. This is a fundamental rule of Python's strong typing system.

Answer

'105'

Answer

105

Answer

15

Question 10

What is the output of the code in the exhibit?

Accepted Answer

[1, 10, 20, 4, 5]. The code uses list slice assignment to replace the elements at indices 1 and 2 (the second and third elements) with the list [10, 20]. Starting from [1, 2, 3, 4, 5], after the assignment lst[1:3] = [10, 20], the list becomes [1, 10, 20, 4, 5]. This matches option B.

Answer

[1, 2, 10, 20, 5]

Answer

[1, 2, 3, 10, 20, 4, 5]

Answer

[1, 10, 20, 3, 4, 5]

Question 11

A Python script uses the following code to open a file: f = open('data.txt', 'w'). The programmer then writes multiple lines to the file. After writing, which of the following is the BEST practice to ensure data integrity?

Accepted Answer

Use a with statement to open the file.. Using a `with` statement ensures that the file is automatically closed when the block exits, even if an exception occurs. This guarantees that all buffered data is flushed to disk, preventing data loss or corruption. It is the recommended best practice in Python for reliable file handling.

Answer

Call f.close() after writing.

Answer

Call f.flush() after writing.

Answer

No action needed; Python automatically closes files.

Question 12

A junior developer is tasked with writing a Python script that reads a list of integers from a file, removes any duplicate numbers, and then writes the unique numbers back to the same file in ascending order. The file 'numbers.txt' currently contains one integer per line. The developer writes the following code:

with open('numbers.txt', 'r') as f:
    numbers = [int(line.strip()) for line in f]
unique = list(set(numbers))
unique.sort()
with open('numbers.txt', 'w') as f:
    for num in unique:
        f.write(str(num) + '
')

The script runs without errors, but the output file contains the numbers in descending order instead of ascending. The developer checks the sort() method and confirms it sorts in ascending order. What is the MOST likely cause of the issue?

Accepted Answer

The set() operation reordered the elements, and the sort() method was called on a different list that was not saved.. The code snippet as shown uses unique.sort() to sort the list in-place and then writes the sorted list, so it would produce ascending order if executed exactly. The discrepancy between the expected ascending order and the reported descending order strongly suggests a deviation from the snippet, such as the developer accidentally calling sort() on a different list (for example, sorting the original numbers list or a temporary copy) and then writing the unsorted unique list. Option B captures this idea: the sort() method was called on a list that was not saved, leading to the unsorted list being written. The other options are not consistent with the provided code: A is incorrect because the numbers are correctly converted to integers; C and D misrepresent file behavior (the file is opened in write mode, not append, and reading does not truncate the file).

Answer

The numbers were read as strings and the sort() method sorted them lexicographically, putting '10' before '2'.

Answer

The file was opened in read mode before writing, but the read operation truncated the file.

Answer

The file was opened in append mode instead of write mode, causing the sorted numbers to be appended after the original unsorted numbers.

Question 13

Match each Python list method to its effect.

Accepted Answer

insert: Inserts an element at a given index.. The correct matches are: insert inserts at an index, remove deletes first occurrence of a value, pop removes and returns an element by index. Common confusions involve swapping append (adds a single element) and extend (adds elements from an iterable).

Answer

append: Extends the list by appending elements from an iterable.

Answer

extend: Adds an element to the end of the list.