Physical changes- any change in the physical properties of the substance is a physical change. Generally physical properties include color, state, size , shape, odour, appearance . In any phyical change, no new substance is formed.
Chemical changes- any change in the chemical properties of the substance is a chemical change. Chemical properties changes only when something new is formed during a reaction.
∴ <u>Part A</u>- 2 H2O(l) → 2 H2(g) + O2(g)
In this, H2 and O2 is produced during the reaction which is different from H20. Thus, it is a chemical change.
<u>Part B</u>- H2O(l) → H2O(s)
In this, only the state of water changes from liquid to solid and no new product is formed. Thus, it is a physical change.
<u>Part C</u><u>-</u>CO2(s) → CO2(g)
In this also, only the state of CO2 changes from solid to gas and no new product is formed. Thus, it is a physical change.
<u>Part D-</u>H2(g) → 2 H(g)
In this reaction, H2 molecule is dissociated into 2 hydrogen atom leading to formation of new products. Thus, it is a chemical change.
Finally, equations that represent physical changes are - B and C
B. H2O(l) → H2O(s)
C. CO2(s) → CO2(g)
