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Mobile App Development Online Assessment Questions & Answers

40 questions for the online assessment stage — 19 easy, 21 medium.

About the online assessment round

Most companies start with an online test: aptitude and reasoning, a few MCQs on core Mobile App Development concepts, and one or two short hands-on tasks. It filters a large number of applicants, so speed and accuracy both count.

Tips for the online assessment round

Practise under a timer: about one minute per MCQ and 15-20 minutes per hands-on task.
Read every option before answering; tests often include two nearly correct choices.
Use a stable internet connection, keep your camera on and avoid switching tabs in proctored tests.
Attempt the questions you are sure about first, then return to the harder ones.

Solved — online assessmentStart practicing

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What is the difference between a debug and release build in mobile apps?

Mobile Development FundamentalsEasy

Show answer

Debug builds include debugging tools, hot reload, assertions and unoptimised code, so they are slower and larger. Release builds are compiled ahead of time, minified, optimised and signed with a release key. In Flutter, debug uses JIT while profile and release use AOT compilation; in React Native, release bundles minified JavaScript precompiled to Hermes bytecode. Always measure performance and test critical flows on release or profile builds.

Write a Dart model class with fromJson and toJson.

Dart and Flutter BasicsEasy

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class Product { const Product({required this.id, required this.name, required this.price}); final String id; final String name; final double price; factory Product.fromJson(Map<String, dynamic> json) => Product( id: json['id'] as String, name: json['name'] as String, price: (json['price'] as num).toDouble(), ); Map<String, dynamic> toJson() => {'id': id, 'name': name, 'price': price}; } // For larger apps use json_serializable or freezed to generate this.

What is the role of a mobile developer in an Agile team?

Mobile Development FundamentalsEasy

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A mobile developer turns user stories and designs into working app features, estimates tasks in sprint planning, raises technical risks early, and collaborates with backend, design and QA. They join standups, demos and retrospectives, review peers' code and keep builds releasable. They also give input on platform constraints like store review times and OS limits, which affect release planning more than in web development.

The API responses are slow on mobile networks. What can the mobile team ask the backend team to change?

Mobile Backend, APIs and FirebaseMedium

Show answer

Ask for pagination with sensible page sizes, gzip or brotli compression, removing unused fields or providing screen-specific endpoints, and aggregated endpoints to avoid multiple sequential calls. Request proper cache headers and ETags so the client can reuse responses. Ask for resized images through a CDN and HTTP/2 or HTTP/3 support. Share measured timings from real devices to justify the requests.

What are isolates and when should you use them?

Dart and Flutter BasicsMedium

Show answer

Isolates are Dart's units of concurrency, each with its own memory and event loop, communicating by messages. Heavy CPU work like parsing a large JSON file, image processing or encryption on the main isolate causes jank. Use Isolate.run or compute to run such work in a separate isolate and return the result. For network or file I/O, async-await is enough because that work is not CPU-bound.

How does token-based authentication work in mobile apps?

Mobile Backend, APIs and FirebaseMedium

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The user signs in and the server returns a short-lived access token, often a JWT, and a longer-lived refresh token. The app stores them securely in Keychain or Keystore-backed storage and sends the access token in the Authorization header. When it expires, the app uses the refresh token to get a new one, retrying the failed request. On logout, tokens are deleted and ideally revoked on the server.

What are privacy declarations required by the app stores?

App Store and Play Store PublishingMedium

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The Play Store requires a data safety form describing what data is collected, shared, encrypted and deletable, plus a privacy policy link and account deletion option for apps with accounts. The iOS App Store requires privacy nutrition labels, a privacy manifest file for the app and listed third-party SDKs describing data use and required reason APIs, and App Tracking Transparency permission before tracking users across apps.

What are runtime permissions and how do they differ between platforms?

Mobile Development FundamentalsMedium

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Both platforms require runtime approval for sensitive features like camera, location, contacts and notifications. Android requires declarations in AndroidManifest.xml and runtime requests for dangerous permissions; iOS requires usage description strings in Info.plist, and the app crashes if a description is missing when requesting. iOS allows asking only once; later the user must change settings. Plugins like permission_handler or react-native-permissions unify the API.

What is clean architecture in a Flutter app?

Flutter State Management and ArchitectureMedium

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Clean architecture separates code into presentation (widgets and state notifiers or blocs), domain (entities, use cases and repository interfaces) and data (repository implementations, API clients, local storage and DTOs). Dependencies point inward, so the domain knows nothing about Flutter or HTTP. It improves testability and lets you swap data sources. For small apps it may be heavy, so many teams keep presentation and data layers and add domain only when logic grows.

How does styling and layout work in React Native?

React Native CoreEasy

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Styles are JavaScript objects created with StyleSheet.create, using camelCase properties like backgroundColor. Layout uses flexbox through the Yoga engine, with flexDirection defaulting to column, unlike the web. Units are density-independent pixels without px. There is no CSS cascade, so styles are applied per component and composed with arrays. Libraries like NativeWind bring Tailwind-style classes, and themes are usually provided through context.

How do you implement authentication flow screens in React Navigation?

React Native Navigation, State and Native ModulesMedium

Show answer

Conditionally render screen groups based on auth state: if the user is signed out, the navigator shows login and signup; when signed in, it shows the app screens. Changing state automatically switches stacks and prevents going back to login with the back button. Restore tokens from secure storage on startup while showing a splash screen. Expo Router offers protected routes for the same pattern.

What are the steps to publish an iOS app on the App Store?

App Store and Play Store PublishingEasy

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Enrol in the developer program, create an App ID and the app record in App Store Connect, and set up signing with certificates and provisioning profiles, often managed automatically by Xcode or EAS. Archive the release build with an incremented build number, upload it, and test through TestFlight. Complete metadata, screenshots, privacy nutrition labels and age rating, then submit for review. After approval, release manually, automatically or in phased release.

What types of tests do you write in Flutter?

Testing, Performance and CI/CDEasy

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Unit tests check pure Dart logic like validators, repositories and state notifiers. Widget tests render a single widget or screen in a test environment with WidgetTester, simulate taps and text entry, and assert what appears, running fast without a device. Integration tests, using the integration_test package, run the full app on a device or emulator for end-to-end flows. Golden tests compare widget screenshots to catch visual regressions.

What is the difference between final and const in Dart?

Dart and Flutter BasicsEasy

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final means a variable is assigned once at runtime and cannot be reassigned. const means the value is a compile-time constant and deeply immutable. In Flutter, const constructors like const Text("Hello") let the framework reuse the same widget instance across rebuilds, skipping unnecessary work. Use const wherever possible for widgets with fixed values; the linter rule prefer_const_constructors helps enforce it.

What are TestFlight and Play testing tracks?

App Store and Play Store PublishingEasy

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TestFlight distributes iOS beta builds to internal testers on your team and external testers, up to 10,000, after a light beta review. Play Console offers internal testing for quick distribution to up to 100 testers, closed testing for selected groups, and open testing for anyone to join. Using these tracks catches device-specific bugs and gathers feedback before production, and staged rollouts then limit risk further.

How do you set up multiple environments such as dev, staging and production in a mobile app?

Mobile Development FundamentalsMedium

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Create build flavours on Android and schemes or configurations on iOS, each with its own app ID suffix, app name, icon and API base URL, so all can be installed side by side. In Flutter, use --flavor with --dart-define-from-file for config values; in React Native, use react-native-config or Expo app config with environment variables. Keep secrets out of the repo and set them in CI.

Write a Flutter widget test that taps a button and checks the counter text.

Testing, Performance and CI/CDEasy

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testWidgets('increments counter on tap', (tester) async { await tester.pumpWidget(const MaterialApp(home: Scaffold(body: Counter()))); expect(find.text('Count: 0'), findsOneWidget); await tester.tap(find.text('Add')); await tester.pump(); expect(find.text('Count: 1'), findsOneWidget); });

How do you reduce app size for Flutter and React Native apps?

Testing, Performance and CI/CDMedium

Show answer

Publish Android App Bundles so users download only their architecture and density resources. In Flutter, use --split-debug-info and --obfuscate, remove unused packages and fonts, compress images and use tree-shaken icons. In React Native, enable Hermes, R8 minification and resource shrinking, and remove heavy libraries. For both, analyse size with tools like flutter build --analyze-size or APK Analyzer and lazy-load large assets.

What are optimistic updates and how do you implement them?

React Native Navigation, State and Native ModulesMedium

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An optimistic update changes the UI immediately as if the server request succeeded, such as liking a post, then rolls back if the request fails. It makes apps feel fast on slow networks. With TanStack Query, use onMutate to update the cache and save the previous value, onError to restore it, and onSettled to refetch. Use it for low-risk actions, not payments.

Explain the core React Native components.

React Native CoreEasy

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View is the basic container, like a div, supporting flexbox layout and styles. Text displays text, and all strings must be inside Text. Image shows images from network or local sources. TextInput handles keyboard input. Pressable handles touches with press states. ScrollView scrolls a small amount of content, while FlatList and SectionList render long lists virtually. SafeAreaView or the safe area context library keeps content away from notches.

How do you implement OTP login with a phone number?

Mobile Backend, APIs and FirebaseMedium

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The user enters a phone number, the backend or an auth service sends an OTP via SMS and returns a verification ID. The user enters the code, which is verified to issue session tokens. On Android, use the SMS Retriever or User Consent API to auto-read the code without SMS permissions; on iOS, set the text content type to one-time code for autofill. Rate-limit requests, expire codes quickly and protect against abuse.

Where should you keep API keys and secrets in a mobile app?

Mobile Backend, APIs and FirebaseEasy

Show answer

Anything bundled in a mobile app can be extracted by decompiling, so never ship true secrets like payment secret keys or admin credentials. Keep them on your backend and let the app call your server. Public client keys, such as maps or Firebase config, are acceptable but should be restricted by app package name, bundle ID and certificate fingerprint. Use environment configuration in CI rather than committing keys to the repository.

What backend options are common for mobile apps?

Mobile Backend, APIs and FirebaseEasy

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Teams build custom REST or GraphQL APIs with Node.js, Java Spring Boot, Python or Go, hosted on cloud platforms. Backend-as-a-Service options like Firebase and Supabase provide authentication, databases, storage, functions and push notifications without managing servers, which suits startups and MVPs. Larger apps often combine a custom backend for business logic with managed services for auth, analytics and messaging.

Compare Provider, Riverpod and Bloc.

Flutter State Management and ArchitectureMedium

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Provider is simple and built on InheritedWidget but depends on BuildContext and can throw provider-not-found errors at runtime. Riverpod, from the same author, is compile-safe, independent of the widget tree, supports async providers and easy overrides for testing. Bloc uses events and states with streams, enforcing strict separation and traceability, popular in large teams and enterprises. Choose based on team familiarity and app complexity.

How would you structure the folder layout of a medium-sized cross-platform app?

Mobile Development FundamentalsMedium

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Organise by feature rather than by type: features/auth, features/cart, features/profile, each containing UI, state logic and data code. Keep shared pieces in core folders such as core/network, core/storage, core/theme and core/widgets or components. Put configuration for environments separately. This keeps related code together, makes ownership clear and lets features be moved into packages later. Enforce the structure with lint rules and code review.

What is Firebase and which services do mobile apps commonly use?

Mobile Backend, APIs and FirebaseEasy

Show answer

Firebase is a mobile and web development platform. Commonly used services are Authentication for email, phone OTP and social logins; Cloud Firestore and Realtime Database for synced data; Cloud Storage for files; Cloud Functions for server code; Cloud Messaging for push notifications; Crashlytics for crash reports; Analytics; Remote Config for feature flags; and App Distribution for testers. FlutterFire and React Native Firebase provide SDKs.

Deep links open the app but land on the home screen instead of the product page. How do you debug it?

React Native Navigation, State and Native ModulesMedium

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Check that the link configuration maps the URL path to the right screen name, including nested navigators, and that path parameters match. Verify verified link setup on both platforms: assetlinks.json for Android and the associated domains entitlement plus the site association file for iOS. Test with adb shell am start and xcrun simctl openurl. Also handle links when the app is cold started versus already running.

The product team wants the same app on mobile and web from one codebase. What would you propose?

React Native Navigation, State and Native ModulesMedium

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With React Native, Expo with Expo Router and React Native Web lets one codebase target Android, iOS and web, with file-based routes working as URLs. With Flutter, the web target exists but suits app-like experiences more than SEO-heavy pages. I would share business logic and most screens, keep SEO landing pages on a web framework, and plan for platform-specific tweaks like hover states and keyboard navigation.

Write a Riverpod provider that fetches data asynchronously and display it in a widget.

Flutter State Management and ArchitectureMedium

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final productsProvider = FutureProvider.autoDispose<List<Product>>((ref) { final repo = ref.watch(productRepositoryProvider); return repo.fetchProducts(); }); class ProductsView extends ConsumerWidget { const ProductsView({super.key}); @override Widget build(BuildContext context, WidgetRef ref) { final products = ref.watch(productsProvider); return products.when( loading: () => const Center(child: CircularProgressIndicator()), error: (e, _) => const Center(child: Text('Failed to load')), data: (items) => ListView(children: [for (final p in items) ListTile(title: Text(p.name))]), ); } }

How do you handle navigation in Flutter with go_router?

Flutter State Management and ArchitectureEasy

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go_router is a declarative, URL-based routing package maintained by the Flutter team. You define GoRoute entries with paths like /product/:id, navigate with context.go or context.push, and read parameters from state.pathParameters. It supports nested navigation with ShellRoute for bottom tabs, redirects for authentication guards, and deep links on mobile and web. It wraps the Router API, which is complex to use directly.

Write a release checklist for a mobile app update.

App Store and Play Store PublishingEasy

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1. Bump version name and build number on both platforms. 2. Run full automated tests and smoke tests on release builds. 3. Verify signing, obfuscation and debug symbol upload. 4. Check new permissions and update store privacy declarations. 5. Update release notes and screenshots if UI changed. 6. Upload to internal track and TestFlight; QA sign-off. 7. Submit for review with reviewer notes and demo account. 8. Start staged rollout at 5 to 10 percent. 9. Monitor crashes, ANRs, reviews and key metrics. 10. Expand rollout or halt and hotfix.

The cart total shows stale values on the checkout screen after items are removed on the cart screen. How do you fix it?

Flutter State Management and ArchitectureMedium

Show answer

Each screen probably holds its own copy of cart data. Move cart state into a single shared state object, such as a Riverpod notifier or a Cubit provided above both screens, and have both screens watch it. All mutations go through that object, which emits a new immutable state. Derived values like total should be computed from the state, not stored separately, so they can never become inconsistent.

Why do Flutter apps need a state management solution beyond setState?

Flutter State Management and ArchitectureEasy

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setState works for local UI state inside one widget, but shared state like the logged-in user, cart or settings must be read and changed by many screens. Passing it through constructors becomes messy, and rebuilding large trees hurts performance. State management libraries separate business logic from UI, make state testable, rebuild only widgets that depend on changed data, and give a clear, predictable flow of updates.

How do you measure performance in a Flutter app?

Testing, Performance and CI/CDMedium

Show answer

Run the app in profile mode on a real device, not debug or emulator. Use Flutter DevTools: the performance view shows frame build and raster times, the CPU profiler finds expensive functions, and the memory view tracks allocations and leaks. Target under about 16 milliseconds per frame for 60 fps. The performance overlay shows UI and raster thread graphs, and rebuild tracking highlights widgets rebuilding too often.

How do you test React Native components?

Testing, Performance and CI/CDEasy

Show answer

Use Jest as the test runner with React Native Testing Library, which renders components and queries them the way users do, by text, role or label. Fire events like fireEvent.press or userEvent, then assert on output. Mock native modules and network calls with jest mocks or MSW. For end-to-end tests on real builds, use Detox or Maestro, which drive the app on emulators and simulators.

Why is TypeScript recommended for React Native projects?

React Native CoreEasy

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TypeScript adds static types to JavaScript, catching mistakes like wrong prop names, missing fields in API responses and undefined values at compile time. It improves editor autocomplete and makes refactoring safer in large codebases. New React Native and Expo templates use TypeScript by default, and Codegen for TurboModules and Fabric components uses typed specs. Combined with strict mode, it significantly reduces runtime crashes.

What is the difference between ListView and ListView.builder?

Dart and Flutter BasicsEasy

Show answer

The default ListView constructor builds all children at once, which is fine for a few items. ListView.builder builds items lazily as they scroll into view, using itemBuilder and itemCount, so it handles long or infinite lists efficiently. For mixed scrolling content like headers, grids and lists together, use CustomScrollView with slivers. For large lists, also set item extent or use prototypeItem to improve scroll performance.

What is dependency injection in Flutter and how is it done?

Flutter State Management and ArchitectureMedium

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Dependency injection supplies objects like API clients and repositories from outside instead of creating them inside widgets or blocs. In Flutter it is commonly done with Riverpod providers, Provider or RepositoryProvider in Bloc, or a service locator like get_it, sometimes with injectable for code generation. It makes code testable because tests can override dependencies with fakes, and it centralises object lifetimes.

What is responsive design in mobile apps and how do you handle different screen sizes?

Mobile Development FundamentalsMedium

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Responsive design means layouts adapt to screen width, orientation, foldables and tablets instead of using fixed sizes. Use flexible layouts, percentages or flex, and breakpoints for compact, medium and expanded widths. In Flutter use LayoutBuilder and MediaQuery.sizeOf; in React Native use flexbox and useWindowDimensions. Respect safe areas for notches and system bars, support text scaling for accessibility, and test on small budget phones.

Explain the mobile app lifecycle states on Android and iOS.

Mobile Development FundamentalsMedium

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Both platforms move apps between foreground active, inactive, background and terminated states. On iOS, an app goes inactive during interruptions like calls, then background, where it gets limited time before suspension. On Android, activities move through resumed, paused and stopped, and the process can be killed in background. Cross-platform apps observe these through AppLifecycleListener in Flutter or AppState in React Native to pause work and save data.

Frequently asked questions

What happens in the Mobile App Development online assessment round?

How do I clear the online assessment round?

Practise under a timer: about one minute per MCQ and 15-20 minutes per hands-on task. Read every option before answering; tests often include two nearly correct choices. Use a stable internet connection, keep your camera on and avoid switching tabs in proctored tests.

Which round comes next?

A typical order is online assessment, telephonic screening, one or two technical rounds, a managerial round and HR. Use the other round pages to practise each stage.

Practise every interview round

Telephonic Interview questions Technical Round questions Managerial Round questions Rapid-Fire questions HR & behavioural questions Full mock interview

More ways to practise

Company-wise Mobile App Development questions Experience-wise Mobile App Development questions Role-wise Mobile App Development questions City-wise Mobile App Development questions Most asked Mobile App Development questions Scenario-based questions Practical / hands-on questions HR & behavioural questions Mobile App Development mock interview Online assessment questions Technical round questions Managerial round questions Mobile App Development topic sheets