Mock 2nd MCQ Python

What will be the output of the following code?

def func(x, y=[]):

y.append(x)

return y

print(func(10), end=" ")

print(func(20))

• [10] [20]

• [10] [10, 20]

• [10] [20]

• [10, 20] [10, 20]

Answer explanation

The default value for y is a mutable list. When the function is called again, the same list is reused, causing updates to persist.

Which of the following statements about keyword arguments is false?

• They improve code readability.

• Keyword arguments can be followed by positional arguments.

• Their order can be different from the function definition.

• They can have default values.

Answer explanation

In Python, keyword arguments must appear after positional arguments, not before.

What will the following code output?

def f(a, args, b=2, *kwargs):

return a, args, b, kwargs

print(f(1, 2, 3, b=4, c=5, d=6))

• (1, (2, 3), 2, {'b': 4, 'c': 5, 'd': 6})

• (1, (2, 3), 4, {'c': 5, 'd': 6})

• (1, (2, 3, 4), {}, {'c': 5, 'd': 6})

• (1, (2,), 3, {'b': 4, 'c': 5, 'd': 6})

Answer explanation

The positional arguments 2, 3 go to args, b is explicitly overridden to 4, and additional named arguments go to *kwargs.

Which of the following will cause an error?

def my_func(a, b=1, c):

pass

• The function definition is valid.

• The order of parameters is invalid.

• Default arguments must precede non-default arguments.

• Both

  The order of parameters is invalid.

  &

  Default arguments must precede non-default arguments.

  is True

Answer explanation

Default arguments must appear after all non-default arguments in the function signature.

SyntaxError: parameter without a default follows parameter with a default

What will happen if a return statement is omitted from a Python function?

• The function will throw an error.

• The function will return None.

• The function will terminate abnormally.

• It depends on the Python version.

Answer explanation

If no return statement is specified, Python functions return None by default.

What will the following code output?

def rec_sum(n):

if n <= 0:

return 0

return n + rec_sum(n - 1)

print(rec_sum(4))

• 4

• 10

• 0

• Infinite Recursion

Answer explanation

The function computes the sum 4+3+2+1+0=10.

Identify the issue in the following recursive code:

def countdown(n):

print(n)

countdown(n - 1)

• Finite recursion

• RecursionError at runtime

• Missing base case

• RecursionError at runtime and Missing base case both options correct

Answer explanation

There’s no base case to stop recursion, which will cause infinite recursion leading to RecursionError.

How can you modify the countdown function to handle negative values gracefully?

def countdown(n):

print(n)

countdown(n - 1)

• Add a base case: if n < 0: return

• Add a base case: if n == 0: return

• Ensure n > 0 before recursive calls.

• Add a base case: if n < 0: return

  and

  Add a base case: if n == 0: return

  are correct

Answer explanation

Adding base cases for n == 0 and n < 0 ensures controlled recursion.

Base Case 1: if n < 0: return

This base case is essential to prevent infinite recursion when n is negative. If n becomes negative, the function will immediately return, stopping the recursive calls.

Base Case 2: if n == 0: return

This base case is necessary to terminate the recursion when n reaches 0. Without this, the function would keep calling itself with decreasing values of n until it reaches a negative number, triggering the first base case.

def countdown(n):

if n < 0:

return

if n == 0:

return

print(n)

countdown(n - 1)

This way, the function will terminate if n is negative or if n reaches zero, ensuring that it handles negative values and zero appropriately.

What will the following code output?

def fib(n):

if n <= 1:

return n

return fib(n - 1) + fib(n - 2)

print(fib(5))

• 5

• 8

• 15

• Infinite recursion

Answer explanation

• fib(5) calls fib(4) and fib(3).

• fib(4) calls fib(3) and fib(2).

• fib(3) calls fib(2) and fib(1).

• fib(2) calls fib(1) and fib(0).
  

• The base cases start to return values:

  • fib(1) returns 1.

  • fib(0) returns 0.

  • fib(2) becomes 1 + 0 = 1.

• 
  

• This process continues, summing up values:

  • fib(3) becomes 1 (fib(2)) + 1 (fib(1)) = 2.

  • fib(4) becomes 2 (fib(3)) + 1 (fib(2)) = 3.

  • Finally, fib(5) becomes 3 (fib(4)) + 2 (fib(3)) = 5.

What will happen if an exception is not caught in Python?

• The program will terminate abnormally.

• The exception will be silently ignored.

• The program will log the exception and continue.

• None of the above.

Answer explanation

Unhandled exceptions terminate the program and print a traceback.