PCEP Timed Hard Questions — 25 Difficult Questions

Question 1

Which THREE of the following statements about Python data types are correct? (Choose three.)

Accepted Answer

Tuples are immutable.. Option C is correct because tuples in Python are immutable, meaning once created, their elements cannot be changed, added, or removed. This immutability makes tuples hashable and usable as dictionary keys, unlike lists.

Answer

Strings are mutable.

Answer

Sets are immutable.

Question 2

A developer writes the following code snippet:
for i in range(3):
    for j in range(2):
        if i == j:
            break
    else:
        print(i, 'outer')
What is the output?

Accepted Answer

2 outer. The code uses nested loops with a `for-else` construct. The `else` block executes only if the inner loop completes without a `break`. When `i == j`, the `break` exits the inner loop, skipping the `else`. For `i=0`, `j=0` triggers `break`; for `i=1`, `j=1` triggers `break`; for `i=2`, the inner loop runs `j=0,1` without any `i==j` (since 2 != 0 and 2 != 1), so the `else` executes, printing `2 outer`. Thus, only option B is correct.

Answer

0 outer
2 outer

Answer

0 outer
1 outer
2 outer

Answer

No output

Question 3

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 4

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

Accepted Answer

[1, 2, 3, 4]. Option A is correct because 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 5

A user enters 'Alice' for name and '30' for age. What is the output?

Accepted Answer

Alice is 30 years old.. Option A is correct because the code `print(name + ' is ' + age + ' years old.')` concatenates the string `'Alice '`, the string `' is '`, the string `'30'`, and the string `' years old.'` using the `+` operator. In Python, the `+` operator performs string concatenation when both operands are strings, and since `input()` always returns a string, both `name` and `age` are strings, so no type error occurs. The output is exactly `Alice is 30 years old.` including the period at the end.

Answer

Alice is 30 years old

Answer

Error: cannot concatenate str

Answer

Name: Alice, Age: 30

Question 6

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 7

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 8

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 9

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 10

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)

Question 11

Given the code:
x = [1, 2, 3]
y = x
y.append(4)
print(x)
What is the output?

Accepted Answer

[1, 2, 3, 4]. Option C is correct because in Python, variables hold references to objects, not the objects themselves. When `y = x` is executed, both `x` and `y` point to the same list object in memory. The `y.append(4)` method modifies that shared list in-place, so the change is reflected when `x` is printed, outputting `[1, 2, 3, 4]`.

Answer

Error

Answer

[1, 2, 3]

Answer

[1, 2, 3, 4, 5]

Question 12

A server logs are stored as a list of tuples: `logs = [('2024-01-10', 'INFO', 'Started'), ('2024-01-10', 'ERROR', 'Disk full')]`. A developer wants to count how many ERROR logs exist. Which code snippet correctly counts them?

Accepted Answer

count = sum(log[1] == 'ERROR' for log in logs). Option B uses a generator expression with `sum()` to count how many tuples in the `logs` list have the second element equal to `'ERROR'`. The expression `log[1] == 'ERROR'` evaluates to `True` (which is treated as 1) or `False` (0) for each tuple, and `sum()` adds them up, giving the correct count of ERROR logs.

Answer

count = logs.count(('ERROR',))

Answer

count = [log for log in logs if log[1] == 'ERROR']

Answer

count = len(logs)

Question 13

A Python script processes a list of tuples representing coordinates: `points = [(1,2), (3,4), (5,6)]`. The developer wants to create a dictionary mapping each coordinate to its distance from origin. Which code correctly creates the dictionary?

Accepted Answer

distances = {point: (point[0]**2 + point[1]**2)**0.5 for point in points}. Option C is correct because it uses a dictionary comprehension to map each tuple (coordinate) to its Euclidean distance from the origin, calculated as `(point[0]**2 + point[1]**2)**0.5`. This correctly produces a dictionary with tuples as keys and float distances as values, matching the requirement exactly.

Answer

distances = {}; for point in points: distances[point] = (point[0]**2 + point[1]**2)

Answer

distances = {}; for point in points: distances[point] = (point[0]**2 + point[1]**2)**0.5

Answer

distances = {point: point[0]**2 + point[1]**2 for point in points}

Answer

distances = [(point, (point[0]**2 + point[1]**2)**0.5) for point in points]

Question 14

Which THREE of the following are valid ways to handle an exception in Python?

Accepted Answer

Using a `try` block with both `except` and `finally` blocks.. Option A is correct because Python's exception handling allows a `try` block to be followed by both `except` and `finally` blocks. The `except` block catches specific exceptions, while the `finally` block always executes (for cleanup), regardless of whether an exception occurred. This combination is fully valid and commonly used for robust resource management.

Answer

Using a `finally` block without a `try` block.

Answer

Using a `try` block with an `else` block but no `except` block.

Question 15

A script calculates total cost: price = 49.95, quantity = 3, tax_rate = 0.08. The developer writes: total = price * quantity * (1 + tax_rate). The result is printed as 161.838. Which best practice is being violated?

Accepted Answer

Not rounding the result to two decimal places for currency.. Option C is correct because when dealing with currency values, best practice dictates rounding to two decimal places to represent cents. The raw result 161.838 is not a valid monetary amount; it should be rounded to 161.84 using `round(total, 2)` or formatted with `:.2f`. This ensures accuracy and avoids confusion in financial calculations.

Answer

Using parentheses unnecessarily.

Answer

Not using an f-string to format the output.

Answer

Using multiplication instead of addition for tax.

Question 16

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

Accepted Answer

512. The expression `2 ** 3 ** 2` uses the exponentiation operator `**`, which in Python is right-associative. This means it is evaluated as `2 ** (3 ** 2)`, not `(2 ** 3) ** 2`. First, `3 ** 2` equals 9, then `2 ** 9` equals 512. Therefore, option A is correct.

Answer

256

Answer

64

Answer

128

Question 17

Refer to the exhibit. What is the output of Line C?

Accepted Answer

33. The function func has parameters a, b (required) and c, d (optional with defaults 10 and 20). Line C calls func with only two arguments (1 and 2), so c and d take their default values. The result is 1+2+10+20 = 33.

Answer

TypeError

Answer

30

Answer

10

Question 18

A developer is troubleshooting a loop that terminates earlier than expected. The code is: i = 0; while i < 5: if i == 3: break; print(i); i += 1. What is the output?

Accepted Answer

0 1 2. The loop starts with i=0 and increments i by 1 each iteration. When i reaches 3, the break statement executes, immediately terminating the loop. Therefore, only i values 0, 1, and 2 are printed, making option D correct.

Answer

0 1 2 3 4

Answer

0 1 2 3

Answer

0 1

Question 19

Which TWO of the following are true about Python's if statement?

Accepted Answer

An if statement can have multiple elif blocks.. if statements can have multiple elif blocks (B) and the condition can be any expression that evaluates to a boolean or truthy/falsy (E).

Answer

if statements cannot be nested.

Answer

An if statement must have a corresponding else clause.

Answer

The condition must be enclosed in parentheses.

Question 20

Which THREE of the following are valid Python variable names?

Accepted Answer

myVar2. Option A is correct because Python variable names must start with a letter or underscore, and can contain letters, digits, and underscores. 'myVar2' begins with a letter and uses only valid characters, making it a legal identifier.

Answer

my-var

Answer

2ndValue