I think it is a but i might be rong
An old penny rusting, remember you can’t undo a chemical change
Answer:
Plastic polymers
Explanation:
Plastic polymers are usually made up of synthetic and semi-synthetic polymers such as polyethylene, polystyrene etc.
Plastic polymers have a unique property called malleability. Malleability is the ability of a substance to be moulded into different sizes and shapes.
When hear is applied plastics gets soft and can be molded into different forms and then it becomes hardened after exposure to air(dried).
The plastic polymers are usually very cheap to produce in large quantities which is why it is very common in industries.
Answer:
Explanation:
Number of molecules of water = 
= Avogadro's number = 
Number of moles is given by
The number of moles of water is .
Answer:The green growing on the penny of copper and the rust forming on the nail of iron are chemical changes. Boiling away salt water, scraping iron filings from a mixture of sand with a magnet, and breaking a rock with a hammer, are physical changes.
Explanation:
