PCEP Practice Test 11 — 15 Questions

Question 1

A function is supposed to modify a list passed as argument by appending an element. However, after calling the function, the original list remains unchanged. Which is the most likely cause?

Accepted Answer

The function reassigns the list parameter instead of mutating it.. In Python, when a list is passed to a function, the parameter refers to the same list object. If the function reassigns the parameter (e.g., `lst = [1, 2, 3]`), it only changes the local reference, not the original list. To modify the original list, the function must mutate it in-place using methods like `append()` or `extend()`, not reassign the parameter.

Answer

The list is immutable.

Answer

The list is a tuple.

Answer

The function uses a local variable that shadows the global list.

Question 2

A team is developing a script that processes user input. They want to ensure that if the user enters a non-numeric value when asked for age, the program does not crash. Which approach should they use?

Accepted Answer

Use int(input()) within a try-except block. Wrapping `int(input())` in a `try-except` block catches the `ValueError` that occurs when `int()` receives a non-numeric string. This prevents the program from crashing and allows graceful handling of invalid input, which is the standard Pythonic approach for robust user input validation.

Answer

Use raw_input() and then int()

Answer

Use input() with a type check after input

Answer

Use a while loop to check if input.isdigit()

Question 3

Arrange the steps to handle an exception in Python using try-except.

Accepted Answer

try block, then except block, then else block, then finally block. Exception handling wraps risky code in try, catches exceptions with except, and optionally includes else and finally.

Answer

try block, then except block, then finally block, then else block

Answer

try block, then else block, then except block, then finally block

Answer

except block, then try block, then else block, then finally block

Question 4

A Python program loads this JSON and accesses the first rule's action. Which expression gives the string "permit"?

Accepted Answer

data["rules"][0]["action"]. It uses the correct indexing to access the first element of the 'rules' list (index 0) and then retrieves the value associated with the key 'action' from that dictionary. This yields the string 'permit' as stored in the JSON data.

Answer

data["rules"][0]["action"][:5]

Answer

data["rules"][0]["action"][0]

Answer

data["rules"][1]["action"]

Question 5

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

Accepted Answer

Tuples are immutable.. 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 6

Which TWO of the following statements about Python's for loop are correct? (Choose Two)

Accepted Answer

It can iterate over any sequence. Option B is correct because Python's for loop is designed to iterate over any iterable object, including sequences such as lists, tuples, strings, and ranges, as well as non-sequence iterables like dictionaries, sets, and generators. Option D is correct because Python's for loop supports an optional else clause that executes after the loop completes normally, i.e., without encountering a break statement. Option A is incorrect because a for loop does not take a while-style boolean condition; it iterates over an iterable, whereas while loops use a condition. Option C is incorrect because a for loop over an empty iterable executes zero times, unlike a do-while construct. Option E is incorrect because Python also provides the while loop, so the for loop is not the only loop.

Answer

It can be used with a while loop condition

Answer

It always executes at least once

Answer

It is the only loop in Python

Question 7

A developer needs to iterate over the indices of a list named 'items' and print each index and its corresponding value. Which loop construct is most appropriate?

Accepted Answer

for i, val in enumerate(items): print(i, val). `enumerate(items)` returns an iterator that yields pairs of (index, value) directly, making it the most Pythonic and efficient way to iterate over both indices and values of a list. It avoids the overhead of calling `items.index(val)` (which is O(n) per iteration) or manually managing `range(len(items))`.

Answer

for val in items: print(items.index(val), val)

Answer

for i in range(len(items)): print(i, items[i])

Answer

for i in items: print(i)

Question 8

A developer wrote: a, b, c = 10, 20, 30; avg = a + b + c / 3; print(avg). What is the output?

Accepted Answer

40.0. Operator precedence in Python dictates that division (/) has higher precedence than addition (+). Therefore, the expression `a + b + c / 3` is evaluated as `a + b + (c / 3)`, which is `10 + 20 + (30 / 3) = 10 + 20 + 10.0 = 40.0`. The result is a float because division always returns a float in Python 3.

Answer

60.0

Answer

20.0

Answer

30.0

Question 9

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 10

Which of the following is a valid Python variable name?

Accepted Answer

_var. (_var) is correct because Python variable names must start with a letter or an underscore, and can contain letters, digits, or underscores. The underscore is a valid starting character, making _var a legal identifier.

Answer

2var

Answer

my-var

Answer

var$name

Question 11

A data analyst needs to read two integers from the user and compute their average as a float. The current code:

a = int(input())
b = int(input())
avg = a + b / 2
print(avg)

The output is always incorrect when a=5 and b=7 (expected 6.0, actual 8.5). The analyst cannot identify the bug. What is the root cause and correct fix?

Accepted Answer

The addition and division have wrong operator precedence; use parentheses: (a + b) / 2.. In Python, the division operator `/` has higher precedence than addition `+`, so `a + b / 2` is evaluated as `a + (b / 2)`, not `(a + b) / 2`. For a=5 and b=7, this computes `5 + (7 / 2) = 5 + 3.5 = 8.5` instead of the expected `(5 + 7) / 2 = 12 / 2 = 6.0`. Adding parentheses around `a + b` forces the addition to occur first, yielding the correct average as a float.

Answer

The input function is not converting correctly; use float(input()) instead.

Answer

The print function is rounding the result; use print("{:.1f}".format(avg)).

Answer

The division operator / always returns an integer; use // instead.

Question 12

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

Accepted Answer

3 == 3. Option C (3 == 3) is correct because the equality operator compares the two integer literals 3 and 3, which are identical values, so the expression evaluates to True. Option E (not False) is correct because the logical not operator inverts the Boolean value False, yielding True. Option A ('a' > 'b') is incorrect because string comparison uses lexicographic ordering by character code point, and 'a' (97) is less than 'b' (98), so the expression is False. Option B (5 > 10) is incorrect because 5 is not greater than 10, so it evaluates to False. Option D (bool(0)) is incorrect because 0 is a falsy value in Python, so bool(0) returns False.

Answer

'a' > 'b'

Answer

5 > 10

Answer

bool(0)

Question 13

A developer wants to store a person's age. Which of these variable names is invalid?

Accepted Answer

3rd_age. In Python, variable names must start with a letter or an underscore, not a digit. Option B (`3rd_age`) begins with a digit, which violates Python's identifier naming rules and will raise a `SyntaxError` if used in code.

Answer

_age

Answer

Age

Answer

age_3

Question 14

Which THREE of the following are Python data types?

Accepted Answer

str. Option A, str, is correct because str is Python's built-in immutable text/string type, used for sequences of Unicode characters. Option C, bool, is correct because bool is a built-in subclass of int representing the two truth values True and False. Option D, float, is correct because float is Python's built-in floating-point type, typically implemented as a C double for real numbers. Option B, math, is not a data type but a standard-library module that provides mathematical functions. Option E, None, is not a data type but the singleton object None, whose type is NoneType.

Answer

math

Answer

None

Question 15

Which TWO of the following are immutable data types in Python?

Accepted Answer

str. Option A (str) is correct because Python strings are immutable: once created, their characters cannot be changed in place, and any operation like concatenation or slicing returns a new string object. Option E (tuple) is correct because tuples are immutable sequences; after creation you cannot add, remove, or reassign their elements, and attempting to do so raises a TypeError. The unmarked options do not belong because set (B), dict (C), and list (D) are all mutable container types, meaning their contents can be modified in place via methods such as add(), update(), or append().

Answer

set

Answer

dict

Answer

list