Hey Vishwa Vishu,

There are 5 apps on Playstore where you can get complete portion to learn about B.arch,

1. NATA Question Papers Download

2. Steps to Architecture

3. NATA app aptitude made easy

4. NATA 2017

5. I-Arch Mock test,

For more details you can check on the following website link,

https://www.google.co.in/amp/s/buddybits.com/2017/07/nata-preparations-apps/amp/

All the best!