PCEP Practice Exam 2 — 20 Questions

Question 1

Match each Python data type to its description.

Question 2

Match each exception type to its description.

Question 3

Match each Python function to its description.

Question 4

Match each Python concept to its description.

Question 5

Refer to the exhibit. What is the output?

Accepted Answer

20
20. The inner function uses nonlocal to modify the variable x from the enclosing scope. After calling inner(), x becomes 20 and is printed. Then outer prints x which is also 20. So output is 20 and 20.

Answer

10
20

Answer

10
10

Answer

20
10

Question 6

A developer wants to read a floating-point number from user input and compute its square. Which code snippet correctly accomplishes this?

Accepted Answer

num = float(input()); result = num ** 2. Option B is correct because it uses `float(input())` to convert the user's input (which is always a string) into a floating-point number, and then computes the square using the exponentiation operator `**`. This ensures that decimal values are handled correctly, which is required for computing the square of a floating-point number.

Answer

num = input(); result = num * num

Answer

result = input() ** 2

Answer

num = int(input()); result = num ** 2

Question 7

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

Accepted Answer

var123. Option B (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 8

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):. Option A is correct because `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 9

A Python program is designed to process user input and store results in a dictionary. The code uses the statement: my_dict[user_key] = value. Under which condition will this statement raise a TypeError?

Accepted Answer

If the key is a list.. Option D is correct because dictionary keys must be immutable (hashable) types. A list is mutable and therefore unhashable, so using it as a key in a dictionary assignment raises a TypeError. The statement `my_dict[user_key] = value` will fail at runtime if `user_key` is a list.

Answer

If the key is None.

Answer

If the key already exists and you try to assign a different value.

Answer

If the key does not already exist in the dictionary.

Question 10

A developer writes a loop to sum numbers from 1 to 10. The code outputs 55, but the expected sum is 55. However, the loop uses a range that includes 0. Which range should be used to achieve the correct sum?

Accepted Answer

range(1,11). Option B (range(1,11)) is correct because range(start, stop) generates numbers from start inclusive to stop exclusive. To sum numbers 1 through 10, the range must start at 1 and end at 11 (so 10 is included). The loop that used range(0,11) included 0, but since adding 0 does not change the sum, the output was still 55 — however, the question asks for the range that achieves the correct sum without including unnecessary values.

Answer

range(0,11)

Answer

range(0,101)

Answer

range(1,10)

Question 11

Which TWO of the following are valid ways to create a list with elements 10, 20, 30?

Accepted Answer

my_list = [x for x in (10,20,30)]. Option A is correct because it uses a list comprehension that iterates over the tuple (10, 20, 30) and creates a new list with the same elements. This is a valid Python syntax for constructing a list from an iterable.

Answer

my_list = list(10, 20, 30)

Answer

my_list = [10; 20; 30]

Question 12

A programmer wants to iterate over a list of strings and print each string in uppercase. Which of the following code snippets will accomplish this?

Accepted Answer

for item in my_list: print(item.upper()). Option D is correct because it correctly calls the `upper()` method on each string `item` in the list `my_list` and prints the result. The `upper()` method returns a new string with all characters converted to uppercase, and the `print()` function outputs that value to the console.

Answer

for item in my_list: print(item.upper)

Answer

for item in my_list: item.upper() print(item)

Answer

for i in my_list: print(my_list[i].upper())

Question 13

A script uses the // operator with negative numbers. For example, -7 // 2 returns -4. The developer expected -3. Which statement best explains this behavior?

Accepted Answer

The // operator performs floor division, which rounds down to the next lower integer.. In Python, the // operator performs floor division, which always rounds down to the next lower integer (toward negative infinity). For -7 // 2, the exact result is -3.5, and floor division rounds down to -4, not -3. This behavior is defined by the Python language specification and differs from truncation toward zero.

Answer

The // operator uses banker's rounding.

Answer

The // operator truncates toward zero for negative numbers.

Answer

The // operator performs integer division with rounding to the nearest even integer.

Question 14

A developer needs to store a large collection of unique user IDs (integers) and quickly check if a new ID already exists. Which data type is most appropriate for this task?

Accepted Answer

set. A set is the most appropriate data type because it stores unordered collections of unique elements and provides O(1) average-time complexity for membership testing using the `in` operator. This makes it ideal for quickly checking if a new user ID already exists without needing to manage keys or maintain order.

Answer

dict

Answer

list

Answer

tuple

Question 15

A list contains strings and numbers: items = ['apple', 10, 'banana', 20]. A programmer wants to create a new list that contains only the strings. Which approach is correct?

Accepted Answer

[item for item in items if type(item) == str]. Option C is correct because `type(item) == str` directly compares the type of each item to the `str` type object, which returns `True` for strings and `False` for numbers. This is a valid and explicit way to filter the list comprehension to only include string elements.

Answer

[item for item in items if item.isdigit()]

Answer

[item for item in items if type(item) is 'str']

Question 16

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. Option B is correct because 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 17

What is the output of the code?

Accepted Answer

0 1 2 4. The code uses a for loop with range(5) to iterate over numbers 0 through 4. Inside the loop, an if statement checks if the current number equals 3; if true, the break statement exits the loop immediately. Therefore, when i becomes 3, the loop terminates before printing 3, so the output is '0 1 2' (each on a new line due to print(i) default behavior). Option C correctly lists the printed values as 0, 1, 2, and then 4 is not printed because the loop breaks before reaching 4.

Answer

No output

Answer

0 1 2 3 4

Answer

0 1 2 4 5

Question 18

A programmer writes code that uses a while loop to process user input until the user types 'exit'. The code currently prints 'Done' after the loop, but it never exits. What is the most likely cause?

Accepted Answer

The variable controlling the loop is not updated inside the loop. Option D is correct because if the variable controlling the loop (e.g., the user's input) is never updated inside the while loop, the loop condition will never become false, causing an infinite loop. In this scenario, the programmer likely reads input once before the loop but does not call input() again inside the loop to update the variable, so the loop never sees the 'exit' value.

Answer

The loop condition is 'while True'

Answer

The print statement is indented incorrectly

Answer

The input function is called outside the loop

Question 19

A developer runs main.py and gets True. They then modify config.py by adding `allowed_ports.append(22)` and run main.py again without restarting the interpreter. What is the output?

Accepted Answer

True. Option D is correct because Python imports modules only once per interpreter session; subsequent imports use the cached module object. Since `config.py` was already imported, modifying the file does not affect the already-loaded list object in memory. The `allowed_ports` list remains unchanged, so the condition that originally returned `True` still holds.

Answer

False

Answer

None

Answer

Error

Question 20

Which TWO of the following code snippets will print the numbers 0, 1, 2, 3, 4?

Accepted Answer

for i in range(0,5): print(i). Option A is correct because `range(0,5)` generates the sequence 0, 1, 2, 3, 4. The `range()` function with two arguments (start, stop) produces numbers from start inclusive up to, but not including, stop. Therefore, iterating with `for i in range(0,5): print(i)` prints exactly 0 through 4.

Answer

for i in range(5+1): print(i)

Answer

for i in range(0,5,2): print(i)

Answer

for i in range(1,6): print(i)