PCPP1 Practice Test 2 — 25 Questions

Question 1

What is the correct way to specify the title of a Tkinter window?

Accepted Answer

root.title('My App'). Tkinter's Tk and Toplevel widget classes expose the title() method, which is the canonical API for setting the window manager caption. Calling root.title('My App') sets the WM_NAME property on the underlying X11/Win32 window, which the OS window manager renders in the title bar. There is no set_title() method on Tkinter widgets, so option A would raise an AttributeError at runtime.

Answer

root.set_title('My App')

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root.name = 'My App'

Answer

root.set_header('My App')

Question 2

You are building a desktop tool with tkinter. A user clicks a button, and while a long file-compression routine runs you want a small window with a progress bar to stay visible and animated; the main application window must remain responsive to the user's clicks throughout. Which approach should you use?

Accepted Answer

Create a tkinter.Toplevel window for the progress bar and run the compression in a separate thread that posts status updates back to the main thread.. Long-running work must never execute on the thread that runs the Tk event loop. Moving the compression onto a worker thread lets the main thread keep dispatching events, so the progress window redraws and the primary window accepts clicks. Because Tkinter widgets may only be touched from the main thread, the worker communicates through a thread-safe queue that the GUI polls periodically.

Answer

Instantiate a second Tk() root, place the progress bar in it, and call its mainloop() from the callback.

Answer

Run the compression loop inside the button's command callback and call update_idletasks() after each chunk is processed.

Answer

Call mainloop() a second time from inside the button's command callback so the progress window gets its own event loop.

Question 3

You are building a Python script that needs to create a ZIP archive containing files from a directory. You want to preserve the directory structure inside the archive. Which approach using the zipfile module correctly adds the file '/data/reports/summary.txt' as 'reports/summary.txt' inside the archive?

Accepted Answer

zipf.write('/data/reports/summary.txt', arcname='reports/summary.txt'). The zipfile.ZipFile.write() method accepts an arcname parameter that specifies the name of the file inside the archive. To preserve a directory structure, you provide a relative path as the arcname, such as 'reports/summary.txt'. This ensures the file is stored with that exact path, regardless of its location on the filesystem.

Answer

zipf.write('/data/reports/summary.txt')

Answer

zipf.add('/data/reports/summary.txt', 'reports/summary.txt')

Answer

zipf.write('/data/reports/summary.txt', arcname='summary.txt')

Question 4

A developer is writing a function that computes the average of a list of numbers. The function should not modify the input list. Which annotation best communicates this intent and aligns with PEP 484 best practices?

Accepted Answer

def average(numbers: Sequence[float]) -> float:. Using Sequence[float] from the typing module communicates that the function accepts any read-only sequence of floats, preserving flexibility while indicating no mutation. This follows PEP 484 guidance to prefer abstract types for parameters. List and Tuple are more specific and imply mutability or a concrete type, which is unnecessarily limiting.

Answer

def average(numbers: List[float]) -> float:

Answer

def average(numbers: Tuple[float, ...]) -> float:

Answer

def average(numbers: list) -> float:

Question 5

How do you set a specific font for a widget?

Accepted Answer

widget.config(font=('Arial', 12)). The 'font' parameter accepts a tuple or string defining font family, size, and style.

Answer

widget.set_font('Arial', 12)

Answer

widget.style('Arial', 12)

Answer

widget.font = 'Arial 12'

Question 6

A developer is writing a module-level variable that holds the maximum number of retries for a network client and will never change during runtime. Which naming convention does PEP 8 recommend for this constant?

Accepted Answer

Use all uppercase letters with underscores between words, such as `MAX_RETRIES`.. PEP 8 names constants using all uppercase letters with underscores separating words, so `MAX_RETRIES` is the recommended form. Python does not enforce immutability, but the naming convention communicates intent to readers and distinguishes constants from ordinary variables and classes. Other capitalizations belong to different categories of names.

Answer

Use CapWords, such as `MaxRetries`, to indicate that the value is a named entity.

Answer

Prefix the name with a single underscore, such as `_MAX_RETRIES`, to mark it as a constant.

Answer

Use lowercase letters with underscores, such as `max_retries`, because Python does not enforce constantness.

Question 7

A developer writes a class `Money` that implements `__eq__` to compare amounts and currencies, but does not implement `__hash__`. Instances of `Money` are then used as keys in a `set`. What is the result?

Accepted Answer

A TypeError is raised when adding an instance to the set because the class is unhashable.. Python disables the inherited `__hash__` when a class overrides `__eq__`, because equal objects must have equal hashes for hash-based collections to work correctly. The developer must define `__hash__` explicitly, hashing the same attributes used in `__eq__`, so that equal `Money` instances produce identical hashes and can be stored in sets or dicts.

Answer

Instances are hashed using the hash of their `__dict__`, so two equal `Money` objects collapse into one set element.

Answer

The set stores instances by identity, so duplicates are allowed and no error occurs.

Answer

Instances can be added to a set, and equality is used for deduplication because `__hash__` defaults to `id()`-based hashing.

Question 8

Which TWO of the following statements about the Python 'requests' library are correct?

Accepted Answer

It uses 'urllib3' internally for connection pooling. Option A is correct because the requests library is built on top of urllib3, which provides the underlying connection pooling and HTTP transport capabilities. Option E is correct because when you call requests.get() or similar top-level functions without using a Session object, requests creates a temporary Session internally, performs the request, and then closes the connection rather than reusing it. Option B is incorrect because requests fully supports HTTPS and TLS/SSL verification. Option C is incorrect because requests is a third-party package that must be installed via pip, not part of the Python standard library. Option D is incorrect because requests is not guaranteed thread-safe for all operations; while Session objects can be used across threads with care, the library does not provide blanket thread-safety guarantees.

Answer

It does not support HTTPS

Answer

It is part of the standard library

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It is thread-safe by default for all operations

Question 9

You are using 'concurrent.futures.ThreadPoolExecutor' to fetch data from multiple REST APIs. What happens if an exception is raised inside a thread?

Accepted Answer

The exception is stored and raised when calling future.result(). Exceptions raised in a future are captured and re-raised when calling result() on the Future object returned by submit().

Answer

The exception is ignored by the ThreadPoolExecutor

Answer

The entire program crashes immediately

Answer

The thread dies silently without notification

Question 10

Which TWO of the following statements correctly describe the behavior of the Tkinter 'pack' geometry manager?

Accepted Answer

The 'side' parameter can be set to 'top', 'bottom', 'left', or 'right'.. Option B is correct because pack()'s 'side' parameter accepts exactly the four values 'top', 'bottom', 'left', and 'right', which determine the edge of the container against which the widget is packed (defaulting to 'top'). Option E is correct because the 'fill' parameter accepts 'x', 'y', 'both', or 'none', controlling whether the widget stretches to fill available space along the horizontal axis, vertical axis, both, or neither. Option A is wrong because pack() honors call order: widgets are allocated space in the sequence pack() is invoked, so order directly affects layout. Option C is wrong because the grid coordinate system belongs to the grid() geometry manager, not pack(). Option D is wrong because absolute X/Y positioning is the domain of the place() geometry manager, whereas pack() uses relative cavity-based allocation.

Answer

The manager automatically ignores the order in which pack() is called.

Answer

Widgets are placed in a grid coordinate system.

Answer

Widgets are positioned at exact X and Y coordinates.

Question 11

Which THREE of the following are valid ways to pass arguments to a function called by a Tkinter button command?

Accepted Answer

command=lambda arg=arg1: my_func(arg). Option A is correct because a lambda with a default argument (arg=arg1) captures the value at definition time and passes it to my_func when the button is clicked, avoiding late-binding issues. Option B is correct because a zero-argument lambda that closes over arg1 defers execution of my_func(arg1) until the button is pressed, which is the standard Tkinter pattern for passing arguments. Option C is correct because functools.partial(my_func, arg1) creates a callable that already has arg1 bound, and Tkinter accepts any callable as the command. Option D is wrong because my_func(arg1=value) is invoked immediately at widget creation, so command receives the function's return value rather than a callable. Option E is wrong for the same reason: my_func(arg1) executes right away and its result is assigned to command, not deferred until the button is clicked.

Answer

command=my_func(arg1=value)

Answer

command=my_func(arg1)

Question 12

Which TWO of the following are valid ways to create a singleton in Python?

Accepted Answer

Using a base class with a custom __new__ method.. Option C is correct because overriding __new__ in a base class lets you intercept instance creation and return the same cached instance every time, which is the canonical Python idiom for enforcing a single instance. Option E is correct because Python modules are imported only once and cached in sys.modules, so module-level state and functions naturally behave as a singleton. Option A is wrong because an uninitialized global variable provides no instance at all and no control over creation. Option B is wrong because returning a new instance on every call is the opposite of the singleton pattern. Option D is wrong because a plain class with no special methods creates a fresh object on each instantiation.

Answer

Using a global variable that is not initialized.

Answer

Using a function that returns a new instance every call.

Answer

Using a standard class without any special methods.

Question 13

Which TWO of the following are valid conventions for naming in Python according to PEP 8?

Accepted Answer

Classes: PascalCase. Option B is correct because PEP 8 specifies that class names should use the CapWords (PascalCase) convention, e.g., class MyClass. Option E is correct because PEP 8 states that variable names should be lowercase with words separated by underscores (snake_case), e.g., my_variable. The unmarked options are incorrect: constants should be UPPER_CASE_WITH_UNDERSCORES, not camelCase (A); modules should be short, all-lowercase names, preferably with underscores, not PascalCase (C); and functions should be lowercase with underscores (snake_case), not camelCase (D).

Answer

Constants: camelCase

Answer

Modules: PascalCase

Answer

Functions: camelCase

Question 14

Which widget is most suitable for displaying multi-line, editable text?

Accepted Answer

tk.Text(). tk.Text is the Tkinter widget designed for multi-line, editable text input, supporting scrolling, indexing, tags, and embedded windows/images. It is the correct choice when users need to enter or edit paragraphs of text. Entry and Label are single-line or read-only, and Listbox is for selecting items from a list.

Answer

tk.Listbox()

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tk.Entry()

Answer

tk.Label()

Question 15

What is the difference between a class-level variable and an instance-level variable?

Accepted Answer

Class-level variables are shared by all instances.. A class-level variable is shared across all instances of the class, whereas an instance-level variable is specific to each object.

Answer

Instance-level variables cannot be modified.

Answer

Class-level variables are always constant.

Answer

Class-level variables are hidden from subclasses.

Question 16

A developer is writing a Python module and wants to follow PEP 8's recommendations for imports. The module currently has the following imports: `import os`, `import sys`, `import requests`, `from collections import defaultdict`. According to PEP 8, how should these imports be grouped and ordered?

Accepted Answer

Standard library imports first, then third-party imports, each group separated by a blank line.. PEP 8 specifies that imports should be grouped in the order: standard library, third-party, and local application/library specific. Each group should be separated by a blank line. In the given scenario, `os`, `sys`, and `collections` are standard library, while `requests` is third-party. Therefore, standard library imports should come first, followed by a blank line, then third-party imports.

Answer

All imports should be sorted alphabetically regardless of origin.

Answer

Imports should be placed on separate lines, and no blank lines are needed between groups.

Answer

Third-party imports first, then standard library imports, to highlight external dependencies.

Question 17

Which TWO of the following are required to successfully write a row to a CSV file?

Accepted Answer

An instance of csv.writer.. To write a row to a CSV file with Python's csv module, you must first create an instance of csv.writer (option B), because csv.writer wraps a file-like object and provides the writerow()/writerows() methods that perform the CSV formatting and writing. You also need a file object opened in write mode (option E), such as one returned by open('file.csv', 'w', newline=''), since csv.writer writes to that underlying file object and cannot write to a path or a read-only handle. Option A is not required because the row data can be any iterable (e.g., tuple, generator), not strictly a list of strings, and the values need not all be strings since the writer converts them. Option C is incorrect because there is no csv.close() function; you close the underlying file object (or use a with block), not the csv module. Option D is incorrect because a predefined dialect is optional — csv.writer defaults to the 'excel' dialect if none is supplied.

Answer

A list of strings to write.

Answer

A call to csv.close().

Answer

A predefined dialect.

Question 18

Which THREE of the following are attributes of the 'requests.Response' object?

Accepted Answer

text. Option B (text) is correct because requests.Response.text returns the response body decoded into a Unicode string using the encoding inferred from the HTTP headers or apparent encoding. Option C (status_code) is correct because requests.Response.status_code holds the integer HTTP status code (e.g., 200, 404) returned by the server. Option E (json()) is correct because requests.Response.json() is a method that deserializes the response body from JSON into Python objects (dict/list), raising a JSONDecodeError if parsing fails. Option A (socket) is not a documented attribute of Response; the underlying socket is managed by urllib3 and accessed via raw/connection internals, not as a direct Response attribute. Option D (connect()) is not a Response method; connect() belongs to HTTPAdapter/urllib3 connection handling, not to the Response object.

Answer

socket

Answer

connect()

Question 19

You are developing a Python script that needs to determine the absolute path of a file located in a directory relative to the script's location. You decide to use the os.path module. Which of the following functions should you use to obtain the absolute path without resolving symbolic links?

Accepted Answer

os.path.abspath(). os.path.abspath() computes an absolute path by combining the current working directory with the given path, normalizing it without resolving symbolic links. This matches the requirement. os.path.realpath() would resolve symlinks, os.path.normpath() only normalizes, and os.path.join() only concatenates components. Thus, abspath is the correct choice.

Answer

os.path.normpath()

Answer

os.path.realpath()

Answer

os.path.join()

Question 20

When using the 'requests' library to perform a GET request, which parameter should be passed to the 'params' argument to include query string parameters in the URL?

Accepted Answer

A dictionary. The requests library's params argument accepts a dictionary (or list of tuples) that it URL-encodes and appends as a query string. Passing a dict like {'q': 'python', 'page': 2} produces ?q=python&page=2 automatically. This is the idiomatic and documented usage for GET query parameters.

Answer

A tuple of values

Answer

A single formatted string

Answer

A list of strings