nothing
yes some chemical reactions are harmful to us. as digestion of food, photosynthesis, decomposition of organic waste are some examples of the useful chemical reactions.
Heat helps chemical reactions to take place. Light can also cause some chemical reactions to take place.
Chemical reactions can produce a variety of products, including gases, liquids, solids, or energy in the form of heat or light. The specific products depend on the reactants involved and the nature of the reaction.
magazines
some chemical changes can be reversed but they are hard to reverse usually
The students analysed the chemical reactions.Detectives watch for the suspect's reactions and body language when questioning them.
Candle and all Chemical reactions
No, not all chemical reactions are reversible. Some reactions are irreversible, meaning they cannot easily be reversed to reform the original reactants.
One example would be: Burning petrol (In your car).
These are not chemical reactions but thermonuclear reactions.
acid and a base
Explain why energy is necessary to chemical reactions, and describe some common sources of energy.