Hello Aspirant.

You're pursuing Physics honours and preparing for CAT along with it you're also learning c++. That course of C++ from Nptel would provide you with a certificate that would embrace your resume but you should be focusing on a single thing rather than moving for multiple fields.

If you're interested in learning c++ then you must do it but should be serious about your preparation about CAT if you wish to make your carrier out of it .

Best of luck !