+ (91) 9319844494
Mon - Fri: 9:00 - 19:00 / All Days Open
info@techstack.in

BOOK FREE DEMO

HOME
PG PROGRAM
POPULAR COURSES
SHORT TERM COURSES
MORE
- About
- Franchise
- Career
- Hire Talent
BLOG

What are you looking for?

HOME
PG PROGRAM
POPULAR COURSES
SHORT TERM COURSES
MORE
- About
- Franchise
- Career
- Hire Talent
BLOG
BOOK FREE DEMO

+ (91) 9319844494
Mon - Fri: 9:00 - 19:00 / All Days Open
info@techstack.in

Data Science Course ( Interview Questions ) Exam

Home
Data Science Course ( Interview Questions ) Exam

Welcome to your ultimate Data Analytics & Data Science Interview Questions Prep!

This page is designed to help you practice and master the most important interview questions from Python, Pandas, NumPy, SQL, and Power BI. Whether you’re preparing for your first analytics role or aiming for a data science career upgrade, these carefully selected MCQs and scenario-based questions will sharpen your problem-solving skills and boost your confidence for real interviews.

Name

Email

Course

Phone

Which data type does range(5) return in Python 3?

Deselect Answer

list

tuple

array

range object

None

Which function is used to create pivot tables in Pandas?

Deselect Answer

pd.pivot_table()

df.pivot()

df.pivot_table()

Both b and c

None

Which module in Python is used for regular expressions?

Deselect Answer

regex

string

pattern

re

None

What will print(type(lambda x: x+1)) return?

Deselect Answer

Error

None

What will df.iloc[0, 1] return?

Deselect Answer

None of the above

Value at first row, second column

Value at second row, first column

Value at first row, first column

None

What is the shape of np.array([[1,2,3],[4,5,6]])?

Deselect Answer

(1,6)

(2,3)

(3,2)

(6,1)

None

Which method writes a DataFrame to Excel?

Deselect Answer

df.save_excel()

df.to_excel()

df.write_excel()

df.to_csv()

None

Python (Frequency Count) You have a list of numbers with millions of elements. Which method is the most efficient way to find the top 3 most frequent numbers? 5 Marks

Deselect Answer

Use list.count() in a loop

Use collections.Counter().most_common(3)

Sort the list and take first 3 values

Convert to Pandas DataFrame and use value_counts()

None

What will df['col1'].unique() return?

Deselect Answer

Index of unique rows

Count of unique values

None

Unique values in column

None

What is the output of sorted([3,1,2])?

Deselect Answer

[3,2,1]

None

Error

[1,2,3]

None

What does df.describe() do?

Deselect Answer

Summarizes numeric columns

Describes data types

Shows index info

Drops missing values

None

What type of data is the number of students in a class?

Deselect Answer

Categorical

Continuous

Discrete

Ordinal

None

Which function replaces missing values with a given number?

Deselect Answer

df.fillna()

df.null_replace()

df.replace()

df.dropna()

None

Which SQL keyword is used to remove duplicate values from a result set?

Deselect Answer

HAVING

DISTINCT

GROUP BY

UNIQUE

None

In SQL, which clause is used to filter aggregated results?

Deselect Answer

ORDER BY

HAVING

WHERE

GROUP BY

None

Which attribute shows the number of rows and columns in Pandas?

Deselect Answer

df.shape

df.size

df.dimension

df.length

None

Which of the following is mutable in Python?

Deselect Answer

Integer

Tuple

String

List

None

Which keyword is used to define a function in Python?

Deselect Answer

define

def

function

fun

None

Which function is used to merge two DataFrames?

Deselect Answer

All of the above

pd.concat()

pd.merge()

pd.join()

None

Which operation does np.dot(A, B) perform?

Deselect Answer

Matrix multiplication

Transpose

Summation

Element-wise multiplication

None

Pandas (Handling Missing Values) You want to replace missing values in some columns with the mean and in others with the mode. Which Pandas approach is most efficient? 5 Marks

Deselect Answer

Use df.fillna(df.mean()) for all columns

Use SQL inside Pandas with pd.read_sql()

Apply df.apply(lambda x: x.fillna(x.mean()) if x.dtype!='object' else x.fillna(x.mode()[0]))

Loop through each column with for and apply fillna()

None

Which method sorts values in Pandas DataFrame?

Deselect Answer

None

df.sort_index()

df.sort_values()

Both a and b

None

In Pandas, which function is used to read a CSV file?

Deselect Answer

pd.read_csv()

pd.csv_read()

pd.read()

pd.load_csv()

None

Which of the following is used for exception handling in Python?

Deselect Answer

error-resolve

handle-error

try-except

do-catch

None

Which of the following creates an array of zeros in NumPy?

Deselect Answer

np.ones()

np.empty()

np.zeros()

np.array(0)

None

Which of the following is NOT a data visualization library in Python?

Deselect Answer

ggplot2

Seaborn

Matplotlib

Plotly

None

What is the output of len(set([1,2,2,3,3,3]))?

Deselect Answer

1

2

6

3

None

NumPy (Conditional Replacement) You have a 2D NumPy array. You want to replace all negative numbers with 0, but only for rows where the row sum is negative. Which is correct? 5 Marks

Deselect Answer

Use nested for loops

arr[np.sum(arr, axis=1) < 0] = np.where(arr[np.sum(arr, axis=1) < 0] < 0, 0, arr[np.sum(arr, axis=1) < 0])

arr[arr < 0] = 0

arr[np.sum(arr, axis=1) < 0] = np.clip(arr, 0, None)

None

In Power BI, which type of join is used by default in relationships?

Deselect Answer

Full Join

Inner Join

Right Join

Left Join

None

Which of the following is not a Python data structure?

Deselect Answer

List

Set

Stack

Dictionary

None

Which of the following is NOT a step in the data analysis process?

Deselect Answer

Data Degradation

Data Cleaning

Data Collection

Model Training

None

What does len("Data Science") return?

Deselect Answer

13

12

10

11

None

What does df.isnull().sum() return?

Deselect Answer

Removes null values

Counts null values per column

Deletes null columns

Fills null values with 0

None

What is the output of list("data")?

Deselect Answer

Error

['data']

['da','ta']

['d','a','t','a']

None

Which SQL clause is used for sorting?

Deselect Answer

ORDER BY

HAVING

SORT BY

GROUP BY

None

Which of the following is NOT a visualization in Power BI?

Deselect Answer

TreeMap

Heatmap

Matrix

Bar chart

None

Power BI (YTD vs LYTD) You want to calculate Year-to-Date (YTD) sales compared to last year. Which DAX formula is correct? 5 Marks

Deselect Answer

YTD Sales = SUM(Sales[Amount])

YTD Sales = CALCULATE(SUM(Sales[Amount]), DATEADD(Sales[Date], -12, MONTH))

YTD Sales = SUMX(Sales, Sales[Amount])

YTD Sales = TOTALYTD(SUM(Sales[Amount]), Sales[Date]) LYTD Sales = CALCULATE([YTD Sales], SAMEPERIODLASTYEAR(Sales[Date]))

None

Which method gives the first 5 rows of a DataFrame?

Deselect Answer

df.head()

df.top()

df.first()

df.tail()

None

Which of the following is used to handle missing values in Python?

Deselect Answer

fillna()

Both a and b

dropna()

None of the above

None

Which Pandas function is used to combine DataFrames vertically?

Deselect Answer

pd.append()

pd.concat()

pd.merge()

pd.join()

None

Which language is used in Power BI for data modeling?

Deselect Answer

DAX

R

SQL

Python

None

Which of the following is NOT a Power BI component?

Deselect Answer

Power View

Power Join

Power Query

Power Pivot

None

Which of the following SQL queries retrieves all students with marks greater than 80?

Deselect Answer

SELECT students WHERE marks > 80;

SELECT * FROM students WHERE marks > 80;

SELECT * FROM students GROUP BY marks > 80;

SELECT * FROM students HAVING marks > 80;

None

SQL (Top N per Group) You need the top 3 customers by total sales in each region. Which SQL query is correct? 5 Marks

Deselect Answer

None of the above

SELECT TOP 3 region, customer_id, SUM(amount) FROM Sales GROUP BY region, customer_id;

SELECT region, customer_id, total_sales FROM ( SELECT c.region, s.customer_id, SUM(s.amount) AS total_sales, ROW_NUMBER() OVER(PARTITION BY c.region ORDER BY SUM(s.amount) DESC) AS rnk FROM Sales s JOIN Customers c ON s.customer_id = c.customer_id GROUP BY c.region, s.customer_id ) t WHERE rnk <= 3;

SELECT region, customer_id, SUM(amount) AS total_sales FROM Sales s JOIN Customers c ON s.customer_id = c.customer_id GROUP BY region, customer_id ORDER BY region, total_sales DESC LIMIT 3;

None

What is the output of bool([])?

Deselect Answer

Error

False

True

None

None

Time's up

Techstack is a renowned Delhi/Ncr based ed-tech company that offers programs to enhance your skills in the tough competitive market.

Mail : info@techstack.in
Call : +91 9319844494

Popular Courses

Executive Digital Marketing Program
Data Analytics and Power Bi Program
Master in Data Science
Post Graduation in Artificial Intelligence
Post Graduation Program in Video Editing
Master in Business Analytics Program
Master in Graphic Designing Program
Python FullStack Web Development Program

Short Term Courses

Advance Digital Marketing Program
Data Science Program
Business Analytics Course
Artificial Intelligence Program
Machine Learning Course
Web Designing Course
Web Development Course
Graphic Designing Course
Video Editing Course
Cyber Security Course
Python Course
React Js Course

Techstack Academy
4th Floor, Plot 7, Lane 2, Westend Marg, Saidulajab, New Delhi - 110030
9319844494

© 2026 - Techstack All rights reserved © Techstack Academy .