Difficult Python and SQL MCQs

What will be the output of the following Python code? x=[1,2,3] x[1:2]=[4,5] print(x)

• [1,4,5,3]

• [1,4,5]

• [4,5,3]

• [1,2,4,5,3]

Answer explanation

The code replaces the slice x[1:2] (which is [2]) with [4,5]. Thus, x becomes [1, 4, 5, 3]. The correct output is [1, 4, 5, 3].

What is the result of the following Python expression? result=2**3**2 print(result)

• 512

• 64

• 128

• 256

Answer explanation

In Python, the expression 2**3**2 is evaluated as 2**(3**2) due to right-to-left associativity of the exponentiation operator. Thus, 3**2 equals 9, and then 2**9 equals 512, making the correct answer 512.

Which of the following statements will correctly define a function that accepts variable number of keyword arguments in Python?

• def func(*args, **kwargs):

• def func(**args, *kwargs):

• def func(*args):

• def func(kwargs, *args):

Answer explanation

The correct choice is 'def func(*args, **kwargs):' because it allows the function to accept a variable number of positional arguments (*args) and keyword arguments (**kwargs), making it flexible for various inputs.

Which of the following will correctly open a file in Python for reading and writing?

• open('file.txt', 'r+')

• open('file.txt', 'w')

• open('file.txt', 'r')

• open('file.txt', 'wb')

Answer explanation

The correct choice is open('file.txt', 'r+')' because it opens a file for both reading and writing. 'r' is for reading only, 'w' is for writing (overwriting), and 'wb' is for writing in binary mode.

What is the result of the following Python code? x=[1,2,3] del x[1] print(x)

• [1,2]

• [1,3]

• [2,3]

• [3]

Answer explanation

The code initializes a list x with [1, 2, 3]. The 'del x[1]' statement removes the element at index 1 (which is 2). Thus, the list becomes [1, 3]. The correct output is [1, 3].

Which of the following Python data structures is mutable?

• Tuple

• String

• List

• Set (in some contexts)

Answer explanation

Among the options, only a List is mutable, meaning its contents can be changed after creation. Tuples and strings are immutable, while sets can be mutable but are not universally so.

What is the correct output of the following code? x={1,2,3,4} x.add(5) x.remove(3) print(x)

• {1,2,4,5}

• {1,2,3,4,5}

• {2,3,4,5}

• {1,2,4}

Answer explanation

The code initializes a set x with {1,2,3,4}. It adds 5, resulting in {1,2,3,4,5}, then removes 3, leaving {1,2,4,5}. Thus, the correct output is {1,2,4,5}.

Which of the following is used to handle exceptions in Python?

• try except

• try block except block

• catch

• except

Answer explanation

In Python, exceptions are handled using the 'try except' construct. The 'try' block contains code that may raise an exception, while the 'except' block defines how to handle that exception. Thus, 'try except' is the correct choice.

What does the zip() function do in Python?

• Joins two lists together element-wise.

• Compresses a list into a smaller version.

• Combines elements from multiple lists into tuples.

• Encrypts a list.

Answer explanation

The zip() function combines elements from multiple lists into tuples, pairing elements with the same index. This is why the correct answer is 'Combines elements from multiple lists into tuples.'

What is the purpose of the lambda function in Python?

• To define a named function.

• To create a function inline without a name.

• To return a boolean value.

• To create a variable in a function.

Answer explanation

The lambda function in Python allows you to create small, anonymous functions inline, which is useful for short operations without the need to formally define a named function.