Phân tích từng giai đoạn và cho biết ở từng giai đoạn đó diễn ra hiện tượng vật lí hay hóa học khi đun nóng đường cát , đường chảy ra (1) .Đường lỏng chuyển sang màu vàng (2), từ màu vàng chuyển dần thành chất rắn màu đen ,có vị đắng và có hơi nước thoát ra.
(1)
(2)
(3)

Hot air balloons float in the air because of the difference in density between cold and hot air. in this problem, you will estimate the minimum temperature the gas inside the balloon needs to be, for it to take off. to do this, use the following variables and make these assumptions: the combined weight of the pilot basket together with that of the balloon fabric and other equipment is w. the volume of the hot air inside the balloon when it is inflated is v. the absolute temperature of the hot air at the bottom of the balloon is th (where th> tc). the absolute temperature of the cold air outside the balloon is tc and its density is ďc. the balloon is open at the bottom, so that the pressure inside and outside the balloon is the same. as always, treat air as an ideal gas. use g for the magnitude of the acceleration due to gravity.

Melting and boiling are endothermic processes. this means that these processes absorb energy from their surroundings in order to occur. use this information and the data you collected in the phase change gizmo to describe what happens to the temperature of water when you boil it, then explain why this result occurs.

The best solution for preventing harm to people and pets from severe hurricanes involves determining and warning residents about what