We can solve this question by keeping this concept in mind. The correct order of density for gas, liquid and solid are :

Gas $< $ Liquid $ < $ Solid. Thus,

Air, exhaust from chimneys       water, honey,          cotton, chalk,iron

                  Gas                              Liquid                           Solid

$ \to \,$ $ \to \,$ $ \to \,$ $ \to \,$ $ \to \,$ $ \to \,$ $ \to \,$ $ \to \,$ $ \to \,$ $ \to \,$ $ \to \,$ $ \to \,$ $ \to \,$ $ \to \,$

                              Increasing order of Density