関連ワード:  ch 4 class 9 science solutions    ch 4 class 9 science ncert solutions    ch 4 science class 9 exercise solutions    ch 4 science class 9 gseb solutions    chapter 1 class 9 science solutions    chapter 2 class 9 science solutions    chapter 3 class 9 science solutions    pol science ch 4 class 9 ncert solutions    cbse class 9 science ch 4 solutions    class 9 science ch 4 explanation