PCEP Practice Exam 4 — 20 Questions

Question 1

Given the code: my_list = [1, 2, 3, 4, 5]. What is the output of print(my_list[-3:-1])?

Accepted Answer

[3, 4]. Python list slicing with negative indices counts from the end of the list. my_list[-3:-1] starts at index -3 (value 3) and goes up to but does not include index -1 (value 5), so it returns [3, 4].

Answer

[4, 5]

Answer

[2, 3]

Answer

[3, 4, 5]

Question 2

Which of the following correctly creates a tuple with a single element 5?

Accepted Answer

t = (5,). In Python, a tuple with a single element requires a trailing comma after the element. Without the comma, parentheses are treated as grouping operators for expression evaluation, not as a tuple literal. Thus, `t = (5,)` creates a tuple containing the integer 5.

Answer

t = (5)

Answer

t = (5)

Answer

t = (5, 5)

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

Which of the following is the most efficient (Pythonic) way to create a list of squares for numbers 0 through 9?

Accepted Answer

squares = [i*i for i in range(10)]. Uses a list comprehension, which is the most Pythonic and efficient way to create a list because it combines iteration and list construction in a single, readable expression. It avoids the overhead of repeated method calls (like `append`) and is faster than `map` with a lambda due to reduced function call overhead.

Answer

squares = []; for i in range(10): squares.append(i*i)

Answer

squares = list(map(lambda x: x*x, range(10)))

Answer

squares = (i*i for i in range(10))

Question 5

Which exception is raised when trying to access a dictionary key that does not exist?

Accepted Answer

KeyError. In Python, when you attempt to access a dictionary key that does not exist using square bracket notation (e.g., `my_dict['nonexistent']`), the interpreter raises a `KeyError`. This is the standard exception for missing dictionary keys, as defined in the Python language specification. The correct answer is A.

Answer

TypeError

Answer

ValueError

Answer

AttributeError

Question 6

A program needs to check if a number is both positive and even. Which expression correctly implements this?

Accepted Answer

if num > 0 and num % 2 == 0:. It uses the logical `and` operator to combine two conditions: `num > 0` (checks if the number is positive) and `num % 2 == 0` (checks if the number is even). Both conditions must be true for the overall expression to be true, which correctly implements the requirement of checking if a number is both positive and even.

Answer

if num > 0 or num % 2 == 0:

Answer

if num > 0 & num % 2 == 0:

Answer

if num > 0 and % 2 == 0:

Question 7

What is the result of bool(0) in Python?

Accepted Answer

False. The bool() function in Python converts any value to a Boolean. The integer 0 is considered a falsy value, so bool(0) returns False. This is because Python defines 0, None, empty collections, and False itself as falsy.

Answer

0

Answer

None

Answer

True

Question 8

Given the code:
```python
name = input('Enter your name: ')
print('Hello, ' + name)
```
If the user enters 'Alice', what is the output?

Accepted Answer

Hello, Alice. The `print('Hello, ' + name)` statement concatenates the string literal `'Hello, '` (which includes a trailing space) with the user input `'Alice'`, producing the output `Hello, Alice`. The `input()` function returns the exact string entered by the user without any extra quotes or formatting.

Answer

Hello,Alice

Answer

Hello, 'Alice'

Answer

Hello, Alice

Question 9

A Python program prompts the user for their age and stores it in a variable. Which is the correct way to convert the input to an integer?

Accepted Answer

age = int(input("Age: ")). The `input()` function in Python always returns a string, and to perform arithmetic operations or numeric comparisons, the string must be explicitly converted to an integer using the `int()` constructor. This is a fundamental requirement for type conversion in Python when handling user input.

Answer

age = str(input("Age: "))

Answer

age = float(input("Age: "))

Answer

age = input("Age: ")

Question 10

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). 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 11

A company has a Python script that imports a module from a package. The package structure is: mypackage/__init__.py, mypackage/module.py. The script uses 'from mypackage import module'. Which file must exist for this import to work?

Accepted Answer

mypackage/__init__.py. For a Python import like 'from mypackage import module' to work, the directory 'mypackage' must be recognized as a package. This requires the presence of an __init__.py file inside it (even if empty), which signals to Python that the directory is a package and allows its submodules to be imported. Option B is correct because __init__.py is the file that makes 'mypackage' a package.

Answer

mypackage.py

Answer

module.py in the current directory

Answer

Only mypackage/module.py is needed

Question 12

Which expression evaluates to False?

Accepted Answer

3 > 4. The expression `3 > 4` evaluates to `False` in Python, as 3 is not greater than 4. All other options evaluate to `True` due to the correct application of comparison operators: `<=`, `==`, and `!=`.

Answer

3 <= 3

Answer

3 == 3

Answer

3 != 2

Question 13

A beginner writes: x = 10; y = "20"; print(x + y). What will happen?

Accepted Answer

It raises a TypeError. Python does not allow implicit type conversion between a string and an integer in an addition operation. The `+` operator with a string and an integer raises a `TypeError`, as Python's dynamic typing requires explicit conversion (e.g., `int(y)` or `str(x)`) for such mixed-type operations.

Answer

It prints 30 as a string

Answer

It prints 1020

Answer

It prints 30

Question 14

A developer writes a function that calculates the area of a rectangle and prints the result inside the function. Later, they need to use this area in another calculation. What should they do to make the function reusable and composable?

Accepted Answer

Modify the function to return the area instead of printing it.. Returning a value from a function allows the caller to capture and reuse that value in subsequent calculations, making the function composable and reusable. Printing the result inside the function (as in the original code) only outputs it to the console and discards the value, preventing further programmatic use. By modifying the function to return the area, the developer can assign the result to a variable and use it in other expressions.

Answer

Store the area in a global variable and access it later.

Answer

Keep the function as is and call it from inside another function.

Answer

Pass the area to the next calculation using a print function argument.

Question 15

Which of the following variable names is NOT valid in Python?

Accepted Answer

2nd_place. Python variable names cannot begin with a digit. The name '2nd_place' starts with '2', which violates Python's identifier naming rules. Valid variable names must start with a letter (a-z, A-Z) or an underscore (_), followed by letters, digits, or underscores.

Answer

My_Var

Answer

_myVar

Answer

myVar2

Question 16

What is the result of the following expression? 3 + 4 * 2 ** 3 // 5

Accepted Answer

9. The expression follows Python's operator precedence: exponentiation (`**`) has the highest precedence, then multiplication (`*`) and floor division (`//`) are evaluated left to right, and finally addition (`+`). First, `2 ** 3` computes to 8. Then `4 * 8` gives 32, and `32 // 5` yields 6 (floor division truncates toward negative infinity, but here it's positive). Finally, `3 + 6` equals 9. Thus, option A is correct.

Answer

7

Answer

6

Answer

11

Question 17

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

Accepted Answer

value_2. `value_2` starts with a letter and contains only letters, digits, and underscores, which satisfies Python's identifier rules. Python variable names must begin with a letter or underscore, and can include letters, digits, and underscores; `value_2` meets all these criteria.

Answer

for

Answer

2nd_value

Answer

val-ue

Question 18

A developer runs the command and sees the output. Which statement about the data type is correct?

Accepted Answer

3.14 is a float in Python.. In Python, numeric literals with a decimal point, such as 3.14, are always interpreted as the built-in float type. Python does not have a separate 'double' type; its float is implemented as a C double (64-bit IEEE 754), but the language itself refers to it as float. This is a fundamental rule of Python's data type system.

Answer

3.14 is a decimal.Decimal type.

Answer

3.14 is a float, but Python also treats it as a double.

Answer

3.14 is a string.

Question 19

A developer needs to iterate over a list of network interfaces and print only the names that start with 'eth'. Which code should be used?

Accepted Answer

for iface in interfaces: if iface.startswith('eth'): print(iface). The `startswith()` string method is the most direct and readable way to check if each interface name begins with the substring 'eth'. This approach avoids unnecessary slicing or substring membership checks, making the intent clear and the code efficient.

Answer

for i in range(len(interfaces)): if 'eth' in interfaces[i]: print(interfaces[i])

Answer

for iface in interfaces: if iface[:3] is 'eth': print(iface)

Answer

for iface in interfaces: if 'eth' in iface: print(iface)

Question 20

What is the result of 'bool(0) and bool(1)'?

Accepted Answer

False. The expression `bool(0) and bool(1)` evaluates to `False` because `bool(0)` converts the integer 0 to `False` (since 0 is falsy in Python), and `bool(1)` converts 1 to `True`. The `and` operator returns `True` only if both operands are truthy; here, `False and True` yields `False`.

Answer

True

Answer

1

Answer

0