https://www.khanacademy.org/science/mh-grade-6-science/x7b6e0e817e3f7b33:substances-in-daily-use/x7b6e0e817e3f7b33:untitled-222/e/natural-and-man-made-substances 2026-07-14T09:20:46.377716139Z Natural and Man-made Substances Exercise Swapna exercise