MERN Stack Quiz (Beginner) - All Questions

This beginner-friendly MERN Stack quiz covers core concepts of MongoDB, Express.js, React, and Node.js with easy and practical MCQs. Perfect for students, freshers, and beginners starting full-stack web development or preparing for interviews.

Question 1: What does MERN stand for?

MongoDB, Express, React, Node
MySQL, Express, React, Node
MongoDB, Ember, React, Node
MongoDB, Express, Redux, Node

Explanation: MERN stands for MongoDB, Express.js, React, and Node.js.

Question 2: Which part of MERN is used for frontend development?

MongoDB
Node.js
React
Express.js

Explanation: React is used to build the frontend UI.

Question 3: Which component of MERN is a NoSQL database?

MySQL
MongoDB
PostgreSQL
Oracle

Explanation: MongoDB is a NoSQL document-based database.

Question 4: Which language is mainly used across the MERN stack?

Python
Java
JavaScript
C#

Explanation: JavaScript is used across frontend and backend in MERN.

Question 5: What is Node.js primarily used for?

UI design
Server-side development
Database storage
Styling

Explanation: Node.js is used to build server-side applications.

Question 6: What is Express.js?

Frontend framework
Database
Node.js framework
Testing library

Explanation: Express.js is a backend framework for Node.js.

Question 7: Which React feature helps build reusable UI?

Hooks
Components
Reducers
Services

Explanation: Components allow reusable UI building blocks.

Question 8: Which command initializes a Node.js project?

node init
npm start
npm init
node start

Explanation: npm init initializes a Node.js project.

Question 9: Which file stores Node.js project dependencies?

index.js
package.json
server.js
config.js

Explanation: package.json stores dependencies and scripts.

Question 10: Which React hook is used to manage state?

useEffect
useState
useRef
useMemo

Explanation: useState is used to manage component state.

Question 11: Which HTTP method is used to fetch data?

POST
PUT
GET
DELETE

Explanation: GET is used to retrieve data from server.

Question 12: Which HTTP method creates new data?

GET
POST
PATCH
DELETE

Explanation: POST is used to create new resources.

Question 13: Which database format does MongoDB use?

Tables
Rows
Documents
Sheets

Explanation: MongoDB stores data as documents.

Question 14: Which MongoDB format is used to store data?

XML
CSV
JSON
BSON

Explanation: MongoDB internally stores data as BSON.

Question 15: Which command starts a React app?

npm build
npm run dev
npm start
npm init

Explanation: npm start runs the React development server.

Question 16: Which React hook is used for side effects?

useState
useEffect
useReducer
useContext

Explanation: useEffect handles side effects like API calls.

Question 17: Which Express method defines routes?

app.route()
app.use()
app.get()
app.config()

Explanation: app.get() defines GET routes.

Question 18: Which middleware parses JSON in Express?

bodyParser
express.json()
jsonParser()
dataParser()

Explanation: express.json() parses incoming JSON.

Question 19: Which tool manages MongoDB locally?

MongoDB Compass
phpMyAdmin
Workbench
Studio

Explanation: MongoDB Compass is a GUI tool for MongoDB.

Question 20: Which React syntax allows HTML in JavaScript?

HTMLX
JSML
JSX
XML

Explanation: JSX allows writing HTML inside JavaScript.

Question 21: Which file is the entry point of a React app?

App.js
index.js
main.js
root.js

Explanation: index.js is the entry point.

Question 22: Which MongoDB command inserts data?

find()
insertOne()
update()
deleteOne()

Explanation: insertOne() adds new data to MongoDB.

Question 23: Which Node.js module handles file system operations?

http
path
fs
os

Explanation: fs module handles file operations.

Question 24: Which HTTP status code means success?

Explanation: 200 indicates a successful request.

Question 25: Which React hook shares data globally?

useState
useEffect
useContext
useMemo

Explanation: useContext shares data across components.

Question 26: Which library is commonly used for routing in React?

React Route
React Router
RouterJS
RouteX

Explanation: React Router handles client-side routing.

Question 27: Which file stores environment variables in MERN apps?

.env
config.js
env.json
vars.txt

Explanation: .env stores environment variables.

Question 28: Which MongoDB method retrieves data?

insert()
find()
add()
push()

Explanation: find() retrieves documents.

Question 29: Which Node.js framework is used in MERN?

NestJS
Express.js
Koa
Hapi

Explanation: Express.js is commonly used in MERN.

Question 30: Which React hook optimizes performance?

useMemo
useState
useEffect
useContext

Explanation: useMemo memoizes expensive calculations.

Question 31: Which port does React usually run on?

3000
8080
4200
5000

Explanation: React runs on port 3000 by default.

Question 32: Which port does Node.js commonly run on?

3000
27017
5000
80

Explanation: 5000 is commonly used for Node servers.

Question 33: Which tool sends HTTP requests for testing APIs?

Git
Postman
Webpack
NPM

Explanation: Postman is used for API testing.

Question 34: Which command installs dependencies?

npm build
npm install
npm start
npm push

Explanation: npm install installs dependencies.

Question 35: Which React hook references DOM elements?

useState
useEffect
useRef
useContext

Explanation: useRef accesses DOM elements.

Question 36: Which MongoDB port is default?

3000
8080
27017
5432

Explanation: MongoDB runs on port 27017.

Question 37: Which Express method handles middleware?

app.use()
app.get()
app.post()
app.listen()

Explanation: app.use() applies middleware.

Question 38: Which React feature updates UI efficiently?

Shadow DOM
Virtual DOM
Real DOM
Browser DOM

Explanation: Virtual DOM improves UI performance.

Question 39: Which Node.js function starts the server?

app.run()
server.start()
app.listen()
node.start()

Explanation: app.listen() starts the server.

Question 40: Which MongoDB operation updates data?

insertOne()
updateOne()
find()
remove()

Explanation: updateOne() updates documents.

Question 41: Which React hook handles component lifecycle?

useState
useEffect
useContext
useRef

Explanation: useEffect handles lifecycle events.

Question 42: Which file usually contains Express routes?

routes.js
index.html
package.json
config.env

Explanation: routes.js commonly defines routes.

Question 43: Which MERN component connects to database?

React
Express
Node
MongoDB

Explanation: Express and Node handle database connections.

Question 44: Which library connects Node.js with MongoDB?

MongoClient
Mongoose
Sequelize
TypeORM

Explanation: Mongoose connects Node.js with MongoDB.

Question 45: Which MongoDB library provides schemas?

MongoClient
Compass
Mongoose
Axios

Explanation: Mongoose provides schema support.

Question 46: Which React hook avoids prop drilling?

useEffect
useState
useContext
useMemo

Explanation: useContext avoids prop drilling.

Question 47: Which MERN layer handles API logic?

Frontend
Database
Backend
UI

Explanation: Backend handles API and business logic.

Question 48: Which format is commonly used in MERN APIs?

XML
SOAP
JSON
CSV

Explanation: JSON is commonly used for APIs.

Question 49: Which Node.js package manages environment variables?

dotenv
envify
config
vars

Explanation: dotenv loads environment variables.

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MERN Stack Quiz (Beginner)

Questions

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