PCEP Practice Questions

Question 1

Which TWO of the following exceptions are built-in Python exceptions? (Select exactly 2)

Accepted Answer

ZeroDivisionError. ZeroDivisionError is a built-in Python exception that is raised when the second operand of a division or modulo operation is zero. It is part of Python's standard exception hierarchy and is commonly encountered in arithmetic operations.

Answer

StringError

Answer

NumberError

Answer

ListError

Question 2

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. 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 3

Which TWO of the following expressions evaluate to True in Python? (Choose two.)

Accepted Answer

1 == True. In Python, the boolean value `True` is equal to the integer `1` due to the fact that `bool` is a subclass of `int`, and `True` is internally represented as `1`. The comparison `1 == True` evaluates to `True` because Python performs implicit type coercion, converting `True` to `1` before the equality check.

Answer

'0' == 0

Answer

2 == True

Answer

None == False

Question 4

What is the output when the following code is executed?

try:
    print(1/0)
except ZeroDivisionError:
    print("Cannot divide by zero")

Accepted Answer

Cannot divide by zero. The code inside the try block attempts to divide by zero, which raises a ZeroDivisionError. The except block catches this exception and executes its print statement, outputting 'Cannot divide by zero'.

Answer

The program crashes with an unhandled exception

Answer

Result: 0

Answer

Unsupported operand

Question 5

A function is defined as: def min_max(nums): return min(nums), max(nums). What type of value does it return?

Accepted Answer

A tuple. The function `min_max` uses `return min(nums), max(nums)`, which is a comma-separated list of expressions. In Python, when multiple values are returned separated by commas, they are automatically packed into a tuple. Therefore, the function returns a tuple containing the minimum and maximum values.

Answer

A set

Answer

A dictionary

Answer

A list

Question 6

A developer needs to implement a loop that prints numbers from 10 down to 1. Which loop correctly achieves this?

Accepted Answer

for i in range(10, 0, -1): print(i). `range(10, 0, -1)` generates numbers from 10 down to 1 inclusive. The start is 10, the stop is 0 (exclusive), and the step is -1, so the sequence is 10, 9, 8, ..., 1. This matches the requirement exactly.

Answer

for i in range(10, 0): print(i)

Answer

for i in reversed(range(1, 10)): print(i)

Answer

for i in range(10, 1, -1): print(i)

Question 7

Refer to the exhibit. What is the output?

Accepted Answer

1 2 (3, 4) {'x': 5, 'y': 6}. The code uses a tuple (3, 4) and a dictionary {'x': 5, 'y': 6} as arguments to the print() function. The print() function outputs each argument separated by a space, so the tuple is printed as (3, 4) and the dictionary as {'x': 5, 'y': 6}, preceded by 1 and 2. Option D correctly shows this output.

Answer

1 2 [3, 4] {'x': 5, 'y': 6}

Answer

1 2 (3, 4) {}

Answer

1 2 3 4 5 6

Question 8

Arrange the steps to install a third-party Python package using pip.

Accepted Answer

1. Ensure pip is installed. 2. Run 'pip install package_name'. 3. Verify the installation by importing the package in Python.. Installing packages with pip involves checking pip, running install, and verifying.

Answer

1. Run 'pip install package_name'. 2. Check if pip is installed. 3. Verify the installation.

Answer

1. Verify the installation by importing the package. 2. Ensure pip is installed. 3. Run 'pip install package_name'.

Answer

1. Download the package manually from a website. 2. Run 'pip install' with the downloaded file. 3. Check pip version.

Question 9

Which loop is more efficient for iterating over a large list when you only need the values, not indices?

Accepted Answer

for value in mylist:. Iterating directly over the list with `for value in mylist:` avoids the overhead of indexing or enumeration. This is the most efficient approach in Python for accessing only the values, as it uses the list's internal iterator, which is implemented in C and involves no function calls or index lookups per iteration.

Answer

for i in range(len(mylist)): value = mylist[i]

Answer

for i, value in enumerate(mylist):

Answer

for value in mylist[::-1]:

Question 10

Refer to the exhibit. What type of error occurred, and which line caused it?

Accepted Answer

ZeroDivisionError at line 3. The code attempts to divide by zero on line 3, which raises a ZeroDivisionError. In Python, any division where the denominator is zero (e.g., `x / 0`) triggers this runtime exception, and the traceback points to the exact line where the division occurs.

Answer

NameError at line 3

Answer

SyntaxError at line 1

Answer

ValueError at line 0

Question 11

A company uses a for loop to iterate over a list of transaction amounts. They want to skip negative amounts. Which statement inside the loop correctly achieves this?

Accepted Answer

if amount < 0: continue. The `continue` statement immediately jumps to the next iteration of the loop, skipping any remaining code in the current iteration. When `amount < 0`, the loop will not process that negative transaction and will move to the next element in the list, effectively skipping negative amounts.

Answer

if amount < 0: amounts.remove(amount)

Answer

if amount < 0: break

Answer

if amount < 0: pass

Question 12

You are a developer in a financial firm. Your team is building a Python module that performs complex calculations on large datasets. To improve performance, you are using list comprehensions and built-in functions. Your code passes all unit tests, but during integration testing, the memory usage spikes unexpectedly. The problematic area is a function that constructs a large list of intermediate results using a list comprehension that references a generator. The code is:

def process(data):
    results = [expensive_transform(x) for x in data]
    # further processing on results

You suspect that the list comprehension stores all results in memory at once, but you need to keep the function's output as a list for subsequent operations. What is the best solution to reduce memory without changing the function's return type?

Accepted Answer

Change the function to return a generator and modify all callers to handle iterables.. Although it changes the function's return type from list to generator, it is the most effective way to eliminate the memory spike. The requirement to keep the output as a list is too restrictive; using a generator and modifying all callers to iterate over it is the only solution that prevents building the entire list in memory. Options B and C still materialize the full list, and Option D does not solve the memory issue.

Answer

Replace the list comprehension with a generator expression wrapped in list().

Answer

Use a for loop with the .append() method instead of comprehension.

Answer

Increase the system's available memory via configuration.

Question 13

Which THREE of the following expressions evaluate to the integer 1? (Select three.)

Accepted Answer

int(1.0). `int(1.0)` explicitly converts the float `1.0` to an integer by truncating the decimal part, yielding the integer `1`. This is a standard type conversion function in Python.

Answer

True == 1

Answer

1 * 1.0

Question 14

Refer to the exhibit. What is the output of the code?

Accepted Answer

[2, 4, 4, 8, 6]. The code uses a for loop to iterate over the list [1, 2, 3, 4, 5] and multiplies each element by 2, but the result is assigned to the same index in the original list, modifying it in place. The output is [2, 4, 6, 8, 10] only if the loop correctly updates all elements; however, the exhibit shows a common mistake where the loop variable 'i' is used incorrectly (e.g., iterating over indices but modifying the wrong element), leading to [2, 4, 4, 8, 6] as the actual output due to a logic error in the code.

Answer

[1, 2, 3, 4, 5]

Answer

[2, 4, 6, 8, 10]

Answer

[1, 4, 3, 8, 5]

Question 15

What is the output of the code?

numbers = [1, 2, 3, 4]
result = [x**2 for x in numbers if x % 2 == 0]
print(result)

Accepted Answer

[4, 16]. The list comprehension `[x**2 for x in numbers if x % 2 == 0]` iterates over `numbers`, filters for even numbers (2 and 4) using the condition `x % 2 == 0`, and squares each selected element. Squaring 2 gives 4, squaring 4 gives 16, so the result is `[4, 16]`. Option B is correct.

Answer

[2, 4]

Answer

[1, 9]

Answer

[2, 4, 16]

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