Auxin is the hormone which is usually synthesised in the young tip of roots and shoots. When light is coming from one side of the plant, it diffuses towards the shady side of the shoot which stimulates the cells to grow longer, resulting in the bending of shoot towards light. Thus auxin promotes phototropism.
In a decomposition reaction, a single reactant breaks down into two or more simpler products. When a decomposition reaction is carried out by heating, it is called thermal decomposition reaction.
