✖️ DON'T CREATE NESTED LISTS WITH THE * OPERATOR.

Because of this, you create a list containing multiple references to the very same inner list.
It looks like you're making a grid, but modifying one row will surprisingly change all of them. This is because the outer list just holds copies of the reference, not copies of the list itself.
Correct — use a list comprehension to ensure each inner list is a new, independent object.

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# hidden error — all inner lists are the same object
matrix = [[]] * 3  # seems to create a 3x0 matrix

# append to the first row
matrix[0].append(99)

# all rows were modified!
print(matrix)  # [[99], [99], [99]]

# ✅ correct version — use a list comprehension
matrix_fixed = [[] for _ in range(3)]

# append to the first row
matrix_fixed[0].append(99)

# only the first row is modified, as expected
print(matrix_fixed)  # [[99], [], []]

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1. What data type is the variable rating = 4.9?
A. Integer
B. Float
C. String
D. Boolean
Correct answer: B.

2. What does the input() function always return?
A. Integer
B. Float
C. Boolean
D. String
Correct answer: D.

3. Which symbol is used to define a comment in Python?
A. //
B. /* */
C. #
D. --
Correct answer: C.

4. What does course[-1] return for a non-empty string?
A. First character
B. Last character
C. Second character
D. Entire string
Correct answer: B.

5. What is the result type of the / operator in Python?
A. Integer
B. Float
C. Boolean
D. String
Correct answer: B.

6. Which operator is used for exponentiation?
A. ^
B. *
C. **
D. //
Correct answer: C.

7. Which logical operator in Python negates a condition?
A. and
B. or
C. not
D. !=
Correct answer: C.

8. What does range(1, 5, 2) generate?
A. 1, 2, 3, 4
B. 1, 3
C. 2, 4
D. 0, 2, 4
Correct answer: B.

9. Which list method removes the last item?
A. remove()
B. delete()
C. pop()
D. clear()
Correct answer: C.

10. What is a tuple best described as?
A. A mutable list
B. A read-only list
C. A key/value store
D. A function container
Correct answer: B.

11. Which dictionary method safely returns a default value if a key is missing?
A. index()
B. find()
C. get()
D. pop()
Correct answer: C.

12. What is returned by a function that has no return statement?
A. 0
B. False
C. Empty string
D. None
Correct answer: D.

13. Which exception is raised when dividing by zero?
A. ValueError
B. TypeError
C. ZeroDivisionError
D. IndexError
Correct answer: C.

14. What is the purpose of the __init__ method in a class?
A. To delete objects
B. To initialize objects
C. To inherit methods
D. To define modules
Correct answer: B.

15. Which command installs a package from PyPI?
A. python install openpyxl
B. install pip openpyxl
C. pip add openpyxl
D. pip install openpyxl
Correct answer: D.

1. What will be the output of the following code?

def f(x, l=[]):
    l.append(x)
    return l

print(f(1))
print(f(2))

A. [1] then [2]
B. [1] then [1, 2]
C. Error due to mutable default
D. [] then []

Correct answer: B.

2. What is the result of this expression?

a = [1, 2, 3]
b = a
a += [4]

A. a = [1,2,3], b = [1,2,3]
B. a = [1,2,3,4], b = [1,2,3]
C. a = [1,2,3,4], b = [1,2,3,4]
D. Raises TypeError

Correct answer: C.

3. What does this code print?

print(bool([]), bool({}), bool(()))

A. True True True
B. False False False
C. False True False
D. True False True

Correct answer: B.

4. What is the output?

x = 10
def outer():
    x = 20
    def inner():
        nonlocal x
        x += 5
    inner()
    return x

print(outer())

A. 10
B. 20
C. 25
D. UnboundLocalError

Correct answer: C.

5. What happens when this code is executed?

class A:
    def __init__(self):
        self.x = 1

a = A()
a.__dict__['x'] = 2
print(a.x)

A. 1
B. 2
C. AttributeError
D. KeyError

Correct answer: B.

6. What is printed?

print([i for i in range(3)] is [i for i in range(3)])

A. True
B. False
C. SyntaxError
D. Depends on Python version

Correct answer: B.

7. What does this code output?

def gen():
    yield from range(3)

print(list(gen()))

A. [0, 1, 2]
B. [1, 2, 3]
C. range(0, 3)
D. Error

Correct answer: A.

8. What is the result?

a = (1, 2, [3, 4])
a[2].append(5)
print(a)

A. Error: tuple is immutable
B. (1, 2, [3, 4])
C. (1, 2, [3, 4, 5])
D. (1, 2, 5)

Correct answer: C.

9. What does this print?

print({i: i*i for i in range(3)})

A. {0, 1, 4}
B. {0: 0, 1: 1, 2: 4}
C. [(0,0),(1,1),(2,4)]
D. Error

Correct answer: B.

10. What is the output?

print(type(lambda x: x))

A. <class 'function'>
B. <class 'lambda'>
C. <class 'callable'>
D. <class 'object'>

Correct answer: A.

11. What happens here?

try:
    1 / 0
finally:
    print("done")

A. Nothing is printed
B. ZeroDivisionError only
C. Prints "done" then raises ZeroDivisionError
D. Prints "done" only

Correct answer: C.

12. What is printed?

x = [1, 2, 3]
print(x[::-1] is x)

A. True
B. False
C. Error
D. Depends on interpreter

Correct answer: B.

13. What does this code demonstrate?

class A: pass
class B(A): pass
print(issubclass(B, A))

A. Duck typing
B. Multiple inheritance
C. Polymorphism
D. Inheritance

Correct answer: D.

14. What is the output?

print(all([0, 1, 2]), any([0, 1, 2]))

A. True True
B. False True
C. True False
D. False False

Correct answer: B.

15. What will this print?

x = 5
def f():
    print(x)
    x = 3

f()

A. 5
B. 3
C. UnboundLocalError
D. NameError

Correct answer: C.

16. What is the result?

a = {1, 2, 3}
b = {3, 2, 1}
print(a == b)

A. False
B. True
C. TypeError
D. Order dependent

Correct answer: B.

17. What does this output?

print(type((i for i in range(3))))

A. <class 'list'>
B. <class 'tuple'>
C. <class 'generator'>
D. <class 'iterator'>

Correct answer: C.

18. What is printed?

x = [1, 2, 3]
y = x.copy()
x.append(4)
print(y)

A. [1,2,3,4]
B. [4]
C. [1,2,3]
D. Error

Correct answer: C.

19. What does this evaluate to?

print(1 == True, 0 == False)

A. False False
B. True True
C. True False
D. False True

Correct answer: B.

20. What is the output?

def f():
    try:
        return 1
    finally:
        return 2

print(f())

A. 1
B. 2
C. None
D. RuntimeError

Correct answer: B.