the cake changed color because it is now pink, size because it expanded in the oven, and shape because it was a liquied and then formed into a solid.. The cake is a chimacal change.
The firework changed in shape because it is spread out, size because it is exploded and spread out , and in color because the colors mix . The firework is a chimacal change.
The hambugar is changed in color because the meat changed from pink to brown. It changed in size because the meat expaned on the grill. Lastly the form of the bugar did not change because it is still the same.