MCQs / Computer Science / Performance, Power, Platform Constraints and Emerging Technologies

Performance, Power, Platform Constraints and Emerging Technologies MCQs — Computer Science

33 multiple-choice questions on Performance, Power, Platform Constraints and Emerging Technologies from Computer Science, each with the correct answer and, where available, a teacher's explanation. Read through them to revise the chapter, then practise the same questions one by one to test yourself.

1. LeakCanary is used to:

  1. Draw icons
  2. Compress images
  3. Detect memory leaks automatically during development
  4. Publish apps

Answer: C) Detect memory leaks automatically during development

Explanation: LeakCanary watches destroyed objects and reports leaks.

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2. On Google Play, a user-perceived crash rate above about 1.09 % may:

  1. Reduce the app's visibility in the store
  2. Have no effect
  3. Increase the developer fee
  4. Delete the app automatically

Answer: A) Reduce the app's visibility in the store

Explanation: Android vitals thresholds affect discoverability.

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3. From Android 14, a foreground service must declare a:

  1. launcher icon
  2. WebView
  3. foregroundServiceType (e.g. location, mediaPlayback)
  4. content provider

Answer: C) foregroundServiceType (e.g. location, mediaPlayback)

Explanation: Service types must be declared in the manifest.

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4. Which WorkManager constraint runs work only while charging?

  1. setRequiresDeviceIdle(false)
  2. setRequiresCharging(true)
  3. setRequiresStorageNotLow(false)
  4. NetworkType.CONNECTED

Answer: B) setRequiresCharging(true)

Explanation: setRequiresCharging defers work until the device is plugged in.

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5. Passkeys are an emerging technology that aims to replace:

  1. Batteries
  2. Passwords
  3. Screens
  4. SIM cards

Answer: B) Passwords

Explanation: Passkeys use public-key cryptography for passwordless sign-in.

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6. "Tail energy" refers to:

  1. Energy saved by dark mode
  2. Battery at 100 %
  3. GPU heat
  4. The cellular radio staying in a high-power state for seconds after a transfer

Answer: D) The cellular radio staying in a high-power state for seconds after a transfer

Explanation: After transmitting, the radio waits before dropping to idle.

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7. OEM battery optimisations that aggressively kill background apps are an example of:

  1. Thermal throttling
  2. App bundles
  3. Doze only
  4. Fragmentation (manufacturer differences)

Answer: D) Fragmentation (manufacturer differences)

Explanation: Different manufacturers change Android behaviour.

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8. Real-world crash and ANR rates of a published app are shown in:

  1. The emulator
  2. Logcat
  3. Android vitals in Play Console
  4. strings.xml

Answer: C) Android vitals in Play Console

Explanation: Vitals aggregate data from users' devices.

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9. A wake lock that is never released causes:

  1. Faster charging
  2. The CPU to stay awake and drain the battery
  3. Smaller APKs
  4. Better GPS

Answer: B) The CPU to stay awake and drain the battery

Explanation: Wake locks prevent the device from sleeping.

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10. Background execution limits on services started in Android:

  1. 5.0
  2. 8.0 Oreo
  3. 10
  4. 14

Answer: B) 8.0 Oreo

Explanation: Oreo limited background services and implicit broadcasts.

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11. Holding a static reference to an Activity Context can cause:

  1. A memory leak
  2. Smaller APK size
  3. Better battery life
  4. Faster startup

Answer: A) A memory leak

Explanation: Static references prevent the activity from being garbage-collected.

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12. Running an AI model directly on the phone's NPU is called:

  1. Polling
  2. Cloud computing
  3. Sideloading
  4. On-device AI

Answer: D) On-device AI

Explanation: On-device inference is private, offline and low-latency.

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13. In Doze mode, network access and background jobs are:

  1. Moved to another phone
  2. Converted to SMS
  3. Deferred to periodic maintenance windows
  4. Run continuously

Answer: C) Deferred to periodic maintenance windows

Explanation: Doze batches background activity into windows.

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14. Window size classes help developers handle which constraint?

  1. Different screen sizes (phones, foldables, tablets)
  2. Network latency
  3. SMS limits
  4. Battery capacity

Answer: A) Different screen sizes (phones, foldables, tablets)

Explanation: They guide adaptive layouts.

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15. Google's SDK for building augmented reality apps on Android is:

  1. ARCore
  2. MapKit
  3. ARKit
  4. Metal

Answer: A) ARCore

Explanation: ARCore is Android's AR platform; ARKit is Apple's.

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16. Google's small on-device model available to Android apps through system AI APIs is:

  1. BERT Large
  2. Gemini Nano
  3. GPT-2
  4. Gemini Ultra

Answer: B) Gemini Nano

Explanation: Gemini Nano runs on supported Android devices.

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17. Which 5G-related concept moves computing closer to users to reduce latency?

  1. Sideloading
  2. Edge computing
  3. Batching
  4. Dead reckoning

Answer: B) Edge computing

Explanation: Edge computing processes data near the network edge.

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18. Which choice saves the MOST battery for an app that needs new messages?

  1. Polling the server every 10 seconds
  2. High-accuracy GPS
  3. Push notifications (FCM) when new data arrives
  4. Keeping a wake lock

Answer: C) Push notifications (FCM) when new data arrives

Explanation: Push wakes the app only when needed.

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19. Which technique improves app startup by pre-compiling important code paths?

  1. More libraries
  2. Larger images
  3. Disabling R8
  4. Baseline Profiles

Answer: D) Baseline Profiles

Explanation: Baseline Profiles let ART AOT-compile critical code at install.

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20. Which Android Studio tool finds heap usage and memory leaks?

  1. Memory Profiler
  2. Vector Asset Studio
  3. Layout Editor
  4. Device Manager

Answer: A) Memory Profiler

Explanation: The Memory Profiler shows allocations and heap dumps.

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21. App Standby Buckets (Android 9) place apps in categories such as:

  1. Free, Paid, Premium
  2. Debug, Release
  3. Small, Medium, Large
  4. Active, Working set, Frequent, Rare and Restricted

Answer: D) Active, Working set, Frequent, Rare and Restricted

Explanation: Buckets limit jobs and alarms based on usage.

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22. Jank (stuttering) happens when frames take longer than about:

  1. 1 ms
  2. 5 seconds
  3. 16 ms (for 60 fps)
  4. 1 second

Answer: C) 16 ms (for 60 fps)

Explanation: Missing the frame deadline causes dropped frames.

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23. StrictMode helps developers by:

  1. Encrypting traffic
  2. Generating signed APKs
  3. Translating strings
  4. Detecting accidental disk or network access on the main thread

Answer: D) Detecting accidental disk or network access on the main thread

Explanation: StrictMode flags slow operations on the UI thread.

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24. Using part of an app without installing it fully is offered by:

  1. Doze
  2. Instant Apps (Android) / App Clips (iOS)
  3. APK Analyzer
  4. TestFlight

Answer: B) Instant Apps (Android) / App Clips (iOS)

Explanation: They load lightweight portions of apps on demand.

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25. Which is NOT a mobile platform constraint?

  1. Limited battery
  2. Unlimited processing power
  3. Variable network
  4. Small screen

Answer: B) Unlimited processing power

Explanation: Mobile CPUs are limited and throttle when hot.

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