PCEP Computer Programming and Python Fundamentals Practice Test 4 — 15 Questions

Question 1

A dictionary: d = {1: 'a', 2: 'b', 3: 'c'}. Which code will cause a KeyError?

Accepted Answer

d[4]. Accessing a dictionary key that does not exist using square bracket notation (d[4]) raises a KeyError. Since the dictionary d has keys 1, 2, and 3, the key 4 is absent, so d[4] triggers the error.

Answer

d.get(4)

Answer

if 4 in d: d[4]

Answer

d.setdefault(4, 'd')

Question 2

Which TWO of the following are valid variable names in Python?

Accepted Answer

total_sum. `total_sum` starts with a letter and contains only letters and underscores, which are allowed in Python identifiers. Python variable names must begin with a letter or underscore and can be followed by letters, digits, or underscores.

Answer

my-var

Answer

2nd_place

Answer

for

Question 3

Which TWO statements about Python lists are true?

Accepted Answer

Lists preserve the order of elements.. Python lists are ordered collections that maintain the insertion order of elements. This means the sequence in which items are added is preserved, and you can access them by their index positions.

Answer

Lists have a fixed size once created.

Answer

Lists are immutable.

Answer

All elements in a list must be of the same type.

Question 4

Which THREE of the following will correctly iterate over all keys and values of a dictionary d = {'a':1, 'b':2}?

Accepted Answer

for k in d: print(d[k]). Iterating over a dictionary directly with `for k in d` yields each key in turn, and `print(d[k])` then accesses the corresponding value. This is a standard and efficient way to iterate over both keys and values without creating intermediate objects.

Answer

for i, k in enumerate(d):

Answer

for v in d.values(): print(v) -- only values

Question 5

Consider the following code:

x = input('Enter a number: ')
print(x + x)

A user enters 5 at the prompt. What is printed?

Accepted Answer

55. 55 because Python's input() function returns a string. When the user enters 5, it is stored as the string '5'. If the code then uses the + operator to concatenate this string with itself (e.g., print(input() + input()) or print(x + x)), the result is '55', not numeric addition.

Answer

10

Answer

5

Answer

25

Question 6

The above JSON is loaded into a Python dictionary named data using json.load(). A developer writes:
print(data['languages'][1][:3])
What is printed?

Accepted Answer

Jav. The JSON data is loaded into a Python dictionary. The key 'languages' maps to a list of strings. Indexing with [1] retrieves the second element, which is 'Java'. Then slicing with [:3] extracts the first three characters, resulting in 'Jav'. Therefore, option B is correct.

Answer

IndexError

Answer

Java

Answer

Pyt

Question 7

Which of the following code snippets will correctly assign the integer 10 to the variable 'x'?

Accepted Answer

x = 10. In Python, the assignment operator is a single equals sign (=), which binds the value on the right to the variable name on the left. The statement `x = 10` assigns the integer 10 to the variable 'x'.

Answer

x == 10

Answer

x := 10

Answer

10 = x

Question 8

A programmer writes the following code:

if x > 5:
print('Greater')

What is the most likely cause of an IndentationError?

Accepted Answer

The print statement is not indented.. In Python, the colon at the end of an if statement signals the start of an indented block. The print statement must be indented (typically 4 spaces) to be part of that block. Without indentation, Python raises an IndentationError because it expects a suite of statements under the if clause.

Answer

The comparison operator is wrong.

Answer

The variable x is undefined.

Answer

The colon after the condition is missing.

Question 9

According to PEP 8, which of the following is the recommended way to name a constant representing the maximum number of retries?

Accepted Answer

MAX_RETRIES. PEP 8 (Python Enhancement Proposal 8) recommends that constants be named using uppercase letters with underscores separating words, i.e., `MAX_RETRIES`. This convention distinguishes constants from regular variables, which use lowercase with underscores, and helps improve code readability and maintainability.

Answer

max_retries

Answer

1st_retry_limit

Answer

maxRetries

Question 10

What is the output of the following code?

print('Hello'.upper())

Accepted Answer

HELLO. The `.upper()` string method in Python returns a new string with all lowercase letters converted to uppercase. The string `'Hello'` contains the characters 'H', 'e', 'l', 'l', 'o'; after applying `.upper()`, it becomes `'HELLO'`. The output is exactly `HELLO` without any additional characters.

Answer

hello

Answer

HELLO!

Answer

Hello

Question 11

Which logical expression evaluates to True given that a = 5 and b = 10?

Accepted Answer

not (a > b). Only option C evaluates to True. Option C: not (5 > 10) = not False = True. Option D: a == b or False = 5 == 10 or False = False or False = False. Options A and B are also False.

Answer

a > b and b < 0

Answer

not (a < b)

Answer

a == b or False

Question 12

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 13

What function is used to read input from the user in Python 3?

Accepted Answer

input(). In Python 3, the built-in `input()` function reads a line from standard input and returns it as a string. This is the standard and simplest way to capture user input, replacing the Python 2 `raw_input()` function.

Answer

read_input()

Answer

sys.stdin.readline()

Answer

raw_input()

Question 14

Consider the following function definition:

def add(a, b):
    return a + b

What is the value of add(3, '4')?

Accepted Answer

TypeError: unsupported operand type(s) for +: 'int' and 'str'. Python's `+` operator is not defined for mixed types like `int` and `str`. When `add(3, '4')` is called, Python attempts to evaluate `3 + '4'`, which raises a `TypeError` because it cannot implicitly convert the string to an integer or vice versa. This is a fundamental type safety rule in Python.

Answer

Error due to missing import

Answer

'34'

Answer

7

Question 15

What is the scope of a variable defined inside a function?

Accepted Answer

Local. In Python, any variable assigned inside a function (without global or nonlocal declarations) has local scope. This means it is only accessible within that function's block and is destroyed when the function returns, as per Python's LEGB (Local, Enclosing, Global, Built-in) rule.

Answer

Global

Answer

Built-in

Answer

Nonlocal