Module quiz: Data and state :React Basics (Meta iOS Developer Professional Certificate) Answers 2026

Question 1

In React, data flows in one way: from a parent component to a child component.

✅ True
❌ False

Explanation:
React one-way (unidirectional) data flow follow karta hai: parent → child.

Question 2

Why is one-way data flow important in React?

✅ It ensures that the data is flowing from top to bottom in the component hierarchy.
❌ It ensures that the data is flowing from bottom to top in the component hierarchy.

Explanation:
Isse app predictable, easy to debug aur maintainable banti hai.

Question 3

True or false? State data is the data inside a component that a component can mutate.

✅ True
❌ False

Explanation:
State component ke andar hota hai aur use setState / useState se update kiya ja sakta hai.

Question 4

What is prop drilling?

✅ Passing data from parent → child → grandchild → further down the tree where it’s needed
❌ Passing data upward from child to parent repeatedly

Explanation:
Prop drilling tab hoti hai jab data bahut zyada levels tak props ke through pass karna padta hai.

Question 5

The distinction between stateful and stateless components is that the latter doesn’t have its own state.

✅ True
❌ False

Explanation:
Stateless components sirf props use karte hain, apna state nahi hota.

Question 6

Choose the correct statement.

❌ Props are mutable and should be changed in children
✅ Props are immutable and should not be changed in children

Explanation:
Props read-only hote hain. Unhe child component me change nahi karna chahiye.

Question 7

Is this code valid?

✅ Yes
❌ No

Explanation:
Function reference pass karna (onClick={handler}) best practice hai.

Question 8

Is this code valid?

✅ Yes
❌ No

Explanation:
Inline arrow functions valid hain (though large apps me avoid karte hain).

Question 9

Select the correct statement: The useState hook…

✅ lets you hook into React state and lifecycle features from a component.
❌ is not part of React
❌ naming function must be counterFunction
❌ should never be called at top level

Explanation:
useState React ka built-in Hook hai jo functional components me state deta hai.

Question 10

The Context API allows you to:

✅ Avoid having to pass state down through multiple levels of components.
❌ Avoid return statements
❌ Avoid modular components

Explanation:
Context API prop drilling ka solution hai.

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