Behaviour of systems when the coefficient matrix is singular — IITM BS previous year questions

Behaviour of systems when the coefficient matrix is singular is part of Invertible Coefficient Matrix, Week 2 in Mathematics 2. Prasnya files every IIT Madras BS previous year question from this subtopic here, each one with a worked explanation. Take the whole set as a timed mock and you get accuracy, pacing and per-question analysis back.