HEY THERE!!!
Hi Monisha Raja,
Yes, you can surely take up ECE (Electronics and Communication Engineering) if you have studied Biology in Class 12 (CBSE), providing you have also studied Mathematics as it is important for ECE. The initial stage is a little difficult since Physics, Circuits, and Programming have some heaviness in it, but once you are consistent and assured yourself you will catch up and do well.
Regarding placements, ECE does have decent opportunities. You can get a place in core electronics companies, IT companies, telecom, embedded systems, and even pure software jobs. I believe if you also learn about the practical aspects (coding, VLSI, IoT, etc) along with your studies; you would have a better chance to get ahead in the job market.
When it comes to phones in the bus, it depends upon college policy I believe. Most colleges do not have an issue with students in buses bringing their phones unless they state otherwise, though I would check with your college's transport or administration.
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