関連ワード:  class 8 science exercise solutions    std 8 science exercise solutions    class 8 science book exercise solutions    ncert class 8 science exercise solutions    cbse class 8 science exercise solutions    class 8 science light exercise solutions    class 8 science friction exercise solutions    class 8 science chapter exercise solutions    class 8 science sound exercise solutions    class 8 science chapter 1 exercise solutions