Answer: melting tin and then cooling it into a mold
Explanation: Physical change is a change in which shape, size or state of the substance is changed and no new substance is formed. Physical changes can be reversed by
Chemical change: When there is a change in rearrangement of atoms which leads to the formation of the new substance.
a) Cutting a gold bar in two pieces and then putting the pieces next to each other: It is a physical change but it is not reversible as original state is not achieved again.
b) burning a match and then relighting it: This is a chemical change as new substances are formed.
c) melting tin and then cooling it into a mold: This is a physical change and is reversible as the original state has been achieved again.
d) combining sodium and chlorine to make the new material of table salt: It is a chemical change.[tex]2Na+Cl_2\rightarrow 2NaCl[/tex]
Melting tin and then cooling it into a mold is the process which showing physical changes are reversible.
Explanation:
The physical change is the change of shape, size or state of the substance. by physical change a new substance is formed. The physical change can be reversible.
The change or rearrangement of atoms is there , the change is called the chemical change. which leads to the formation of new substance.
(A) The physical change which is not reversible is cutting a gold bar into pieces next to each other.
(B)Burning a match and then realigning is a chemical change as new substance are formed.
(C)Melting tin and then cooling it into a mold: This is a physical change and it is reversible as its original state is achieved again.
(D)Combination of sodium and chlorine to make the new material of table salt as it is a chemical change.
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