Question 1

1.What is React primarily used for?

Accepted Answer

C. Building user interfaces

Answer

A. Backend development

Answer

B. Styling websites

Answer

D. Writing SQL queries

Question 2

2. Which tool opens the app in a browser on run?

Accepted Answer

D. Dev Server

Answer

B. Babel

Answer

C. React CLI

Answer

A. Webpack

Question 3

3. What is the command to install create-react-app globally?

Accepted Answer

C. npx create-react-app

Answer

B. npm install create-react-app

Answer

A. npm create react-app

Answer

D. create-react-app init

Question 4

4. Which command runs a newly created React app?

Accepted Answer

B. npm start

Answer

D. npm run

Answer

C. npm build

Answer

npm dev

Question 5

5. What is the default port for a React development server?

Accepted Answer

A. 3000

Answer

B. 8000

Answer

C. 5000

Answer

D. 8080

Question 6

6. React environment setup requires:

Accepted Answer

C. Node.js and npm

Answer

B. Docker

Answer

A. Apache

Answer

D. Python

Question 7

7.  React is typically developed with which code editor?

Accepted Answer

C. Visual Studio Code

Answer

Sublime Text

Answer

D. NetBeans

Answer

B. Eclipse

Question 8

8. Props in React are used to:

Accepted Answer

b) Pass data from parent to child components

Answer

c) Directly update the DOM

Answer

a) Manage internal component data

Answer

d) Store API keys securely

Question 9

9. React is typically developed with which code editor?

Accepted Answer

C. Visual Studio Code

Answer

B. Eclipse

Answer

A. Sublime Text

Answer

D. NetBeans

Question 10

10. In which folder does create-react-app place React components by default?

Accepted Answer

C. /src

Answer

A. /public

Answer

D. /assets

Answer

B. /node_modules

Question 11

11.Which file in React contains the root DOM node?

Accepted Answer

A. index.js

Answer

C. setupTests.js

Answer

B. App.js

Answer

D. manifest.json

Question 12

12. Which feature was introduced in React 16?

Accepted Answer

C. Suspense

Answer

B. Hooks

Answer

A. JSX

Answer

D. Virtual DOM

Question 13

13. What is the latest stable version of React as of 2024?

Accepted Answer

C. React 18

Answer

A. React 16

Answer

D. React 19

Answer

B. React 17

Question 14

14. JSX was introduced in which React version?

Accepted Answer

D. 0.12

Answer

B. 0.5

Answer

A. 0.3

Answer

C. 0.10

Question 15

15.JSX in React is mainly used for?

Accepted Answer

Writing HTML-like syntax inside JavaScript code

Answer

Writing SQL queries in JavaScript

Answer

Designing CSS animations

Answer

Defining database schemas

Question 16

16. React 17 focused on:

Accepted Answer

C. Easier upgrades

Answer

A. Performance boosts

Answer

B. Feature removal

Answer

D. Better CSS support

Question 17

17. Which of the following is a valid type of React component?

Accepted Answer

Functional and Class-based

Answer

Parent and Child

Answer

Static and Dynamic

Answer

Public and Private

Question 18

18. The difference between props and state in React is:

Accepted Answer

a) Props are immutable, state is mutable

Answer

d) State is immutable, props are mutable

Answer

c) Props are for backend, state is for frontend

Answer

b) Both are immutable

Question 19

19. Which of the following best describes a React Component?

Accepted Answer

b) A small reusable UI unit in React applications

Answer

c) A database record

Answer

A) piece of hardware in a computer system

Answer

d) A CSS selector

Question 20

20. Class-based components extend which built-in class in React?

Accepted Answer

React.Component

Answer

React.Element

Answer

React.Module

Answer

React.Object

Question 21

21. Which symbol is used for embedding JavaScript expressions inside JSX?

Accepted Answer

b) {}

Answer

d) <>

Answer

c) []

Answer

a) ()

Question 22

22. Which of the following is NOT a React lifecycle method?

Accepted Answer

d) getElementById

Answer

b) componentWillUnmount

Answer

a) componentDidMount

Answer

c) render

Question 23

23.  Class-based components extend which built-in class in React?

Accepted Answer

c) React.Component

Answer

d) React.Element

Answer

b) React.Object

Answer

A)React.Module

Question 24

24. Functional components in React are usually written as:

Accepted Answer

b) Functions that return JSX

Answer

d) HTML-only templates

Answer

c) SQL queries

Answer

A)Java classes

Question 25

25. Which of the following best describes a React Component?

Accepted Answer

b) A small reusable UI unit in React applications

Answer

c) A database record

Answer

A)A piece of hardware in a computer system

Answer

d) A CSS selector

Question 26

26.  To trace props and state, which tool is best?

Accepted Answer

C). React Developer Tools

Answer

B). Redux Logger

Answer

D). Node Monitor

Answer

A)Webpack Analyzer

Question 27

27.  What happens if npm start fails due to a port 
conflict?

Accepted Answer

C. React offers to use another port

Answer

B. React crashes

Answer

D. The browser closes

Answer

a) App stops

Question 28

28.Which of these helps inspect React component state?

Accepted Answer

C). React Developer Tools

Answer

A) Babel

Answer

D). ESLint

Answer

B) Redux Logger

Question 29

29.Which command is used to create production build?

Accepted Answer

B). npm run build

Answer

C). npm export

Answer

A) npm compile

Answer

D). npm finalize

Question 30

30. Why are version updates important in React?

Accepted Answer

C). Add new features and fix bugs

Answer

B). Allow server rendering

Answer

A)Improve backend speed

Answer

D). Remove JSX

Question 31

31.  Which file contains dependencies in a React project?

Accepted Answer

B. package.json

Answer

README.md

Answer

D. node_modules

Answer

C. App.js

Question 32

32. Component Composition in React means:

Accepted Answer

b) Nesting and reusing components inside other components

Answer

a)  Combining multiple functions in one file

Answer

d) Splitting a class into functions

Answer

c) Writing CSS inside JavaScript

Question 33

33. To install React manually, which package is required?

Accepted Answer

C. react

Answer

B. react-core

Answer

D. react-main

Answer

A)react-package

Question 34

34.  Which tool opens the app in a browser on run?

Accepted Answer

D. Dev Server

Answer

B. Babel

Answer

C. React CLI

Answer

a)Webpack

Question 35

35. Which browser tool is commonly used to debug React apps?

Accepted Answer

B). DevTools

Answer

a)  ReactFire

Answer

C). React Native

Answer

D). Redux Monitor

Question 36

36. To view console errors in React, open:

Accepted Answer

B). Chrome Console

Answer

a) App.js

Answer

D). Node Dashboard

Answer

C). Git Bash

Question 37

37. React environment setup requires:

Accepted Answer

C). Node.js and npm

Answer

B). Docker

Answer

a) Apache

Answer

D). Python

Question 38

38. Which npm command reinstalls all dependencies?

Accepted Answer

C). npm install

Answer

B. npm reset

Answer

D). npm force

Answer

A) npm cache clear

Question 39

39.  Which error indicates a JSX syntax issue?

Accepted Answer

C). SyntaxError: Unexpected token '<'

Answer

B). Uncaught ReferenceError: JSX is not defined

Answer

D). 404 Not Found

Answer

A) TypeError: undefined is not a function

Question 40

40. Which version brought concurrent features?

Accepted Answer

D). 18

Answer

C). 17

Answer

A)15

Answer

B). 16

Question 41

41. Where is the Hello World message typically written
 in React?

Accepted Answer

B). App.js

Answer

D). main.css

Answer

C). index.html

Answer

A) index.js

Question 42

42.  Which version introduced React.StrictMode?

Accepted Answer

B). 16.3

Answer

C). 17

Answer

D). 18

Answer

A) 15

Question 43

43. JSX stands for:

Accepted Answer

A)JavaScript XML

Answer

C). Java Simple XSL

Answer

B). Java Source XML

Answer

D). JavaScript Exchange

Question 44

44.  Which type of architecture does React follow?

Accepted Answer

C). Flux

Answer

B). MVVM

Answer

A)MVC

Answer

D). MVP

Question 45

45. JSX requires how many root elements per component?

Accepted Answer

A) One

Answer

D). None

Answer

B). Two

Answer

C). Unlimited

Question 46

46. What is the purpose of App.js?

Accepted Answer

B). It defines the root component

Answer

C). It defines webpack

Answer

A)It sets up the package manager

Answer

D). It handles the backend logic

Question 47

47. What is a major benefit of using React?

Accepted Answer

C). Component reusability

Answer

D). Full backend support

Answer

B). Easy routing

Answer

A)Supports multiple languages

Question 48

48. The public folder contains:

Accepted Answer

C). Static files

Answer

B). API logic

Answer

D). JSX files

Answer

A) Source code

Question 49

49. React is best suited for building:

Accepted Answer

C). Single-page applications

Answer

D). Server-side apps

Answer

B). Desktop applications

Answer

A) Command-line apps

Question 50

50.  React can be used with:

Accepted Answer

C). Any JavaScript library

Answer

A) Only JavaScript

Answer

B). Any UI library

Answer

D). Only CSS frameworks

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