Yes, you can attempt mock tests on a mobile phone or tablet app. Here are the details:

Convenience and Accessibility:
- Using a mobile phone or tablet app to attempt mock tests offers convenience and accessibility. You can access the app anytime and anywhere, allowing you to practice and prepare for exams at your own pace and convenience.
- It eliminates the need for a computer or laptop, as most people carry their mobile phones or tablets with them at all times.

User-friendly Interface:
- Mobile phone and tablet apps are designed with user-friendly interfaces, making it easy for candidates to navigate through the mock tests and answer questions.
- The layout of the app ensures that the screen is optimized for smaller devices, providing a seamless and comfortable user experience.

Interactive Features:
- Mobile phone and tablet apps often include interactive features such as timers, progress trackers, and instant feedback on answers.
- These features enhance the learning experience by simulating the real exam environment and providing immediate insights into your performance.

Notification and Reminders:
- Many mobile phone and tablet apps send notifications and reminders to help you stay on track with your mock test schedule.
- These reminders can be customized according to your preferences, ensuring that you never miss a practice session.

Offline Access:
- Some mobile phone and tablet apps allow you to download mock tests and practice them offline.
- This is especially beneficial for individuals who may not always have access to a stable internet connection.

Progress Tracking:
- Mobile phone and tablet apps often come with progress tracking features that allow you to monitor your performance over time.
- You can view your scores, identify areas of improvement, and track your overall progress as you continue to practice and attempt mock tests.

Conclusion:
In conclusion, using a mobile phone or tablet app to attempt mock tests offers convenience, accessibility, and a user-friendly experience. These apps provide interactive features, notifications, offline access, and progress tracking, making them an excellent tool for UPSC exam preparation.