When a chemical reaction occurs,
reactants interact to form products with different chemical and physical properties
reactants interact to form products with different numbers of atoms
products react to form several reactants with different chemical properties

A. reactants interact to form products with different chemical and physical properties.
Chemical reactions change the element, because the atoms rearrange to form a different product.

Having a different number of atoms doesn't change an element, and in chemical reactions no new atoms are created and no atoms are destroyed. You should check out Dalton's atomic theory to find out more about this. And chemical reactions don't form several reactants.

Question 4 i think is expository

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