CS441 MCQs Explained

Q1. What is the correct file extension for Python files?

1. .pt
2. .py [Correct]
3. .pyt
4. .python

Correct answer: .py [Correct]

Explanation: Python scripts and modules use the '.py' extension so they can be recognized and executed by the Python interpreter.

Q2. Which data structure is immutable in Python?

1. List
2. Set
3. Dictionary
4. Tuple [Correct]

Correct answer: Tuple [Correct]

Explanation: Tuples are immutable, meaning their elements cannot be changed, added, or removed after creation, unlike Lists, Sets, and Dictionaries.

Q3. What is the output of: len([1, 2, 3, 4])?

1. 3
2. 4 [Correct]
3. 5
4. Error

Correct answer: 4 [Correct]

Explanation: The len() function returns the total number of items in an iterable. The list [1, 2, 3, 4] contains exactly 4 integer elements.

Q4. What is Pandas mainly used for?

1. Machine learning
2. Numerical computation
3. Data manipulation and analysis [Correct]
4. 3D graphics

Correct answer: Data manipulation and analysis [Correct]

Explanation: Pandas is a powerful library built on NumPy specifically designed for structured data manipulation, analysis, and cleaning using DataFrames and Series.

Q5. What does df.head() do in Pandas?

1. Returns last 5 rows
2. Returns first 5 rows [Correct]

Correct answer: Returns first 5 rows [Correct]

Explanation: By default, the .head() method returns the first 5 rows of a DataFrame to help quickly inspect the data.

Q6. Which method is used to read a CSV file using Pandas?

1. read_file
2. read_csv [Correct]
3. open_csv
4. load_csv

Correct answer: read_csv [Correct]

Explanation: The pd.read_csv() function is the standard method in Pandas for loading comma-separated values (CSV) into a DataFrame.

Q7. What library is commonly used for numerical computing in Python?

1. Pandas
2. NumPy [Correct]
3. TensorFlow
4. Seaborn

Correct answer: NumPy [Correct]

Explanation: NumPy provides support for large, multi-dimensional arrays and matrices, along with mathematical functions to operate on these arrays efficiently.

Q8. What does the .shape attribute of a DataFrame return?

1. Size of a column
2. Number of columns
3. Tuple of (rows, columns) [Correct]
4. Data types

Correct answer: Tuple of (rows, columns) [Correct]

Explanation: The .shape attribute returns a tuple representing the dimensionality of the DataFrame, formatted as (number_of_rows, number_of_columns).

Q9. Which of the following is not a data type in Python?

1. Integer
2. Float
3. Character [Correct]
4. String

Correct answer: Character [Correct]

Explanation: Python does not have a distinct "character" data type. A single character is simply treated as a string of length 1.

Q10. How do you insert comments in Python code?

1. //
2. --
3. # [Correct]
4. %%

Correct answer: # [Correct]

Explanation: The hash symbol (#) is used in Python to indicate a single-line comment, which is ignored by the interpreter.

Q11. What is the keyword to define a function in Python?

1. def [Correct]
2. func
3. lambda
4. function

Correct answer: def [Correct]

Explanation: The 'def' keyword is used to declare and define a new custom function block in Python.

Q12. What is the correct way to import the NumPy library?

1. import numpy as np [Correct]
2. import NumPy
3. include numpy
4. use numpy

Correct answer: import numpy as np [Correct]

Explanation: The standard convention is to import numpy with the alias 'np' for shorter syntax when calling its methods.

Q13. How do you handle exceptions in Python?

1. if-else
2. do-while