Question

Classify the following as Physical and Chemical change:
-Cutting of Trees
-Melting of butter in a pan
-Rusting of almirah
-Boiling of water to form steam
-Passing of electric current through water and water breaking into hydrogen and oxygen gases.
-Dissolving common salt in water
-Making a fruit salad with raw fruits
-Burning of paper and wood

Answer 1

Hint:Physical change is that change in which the physical properties of matter change like change of state of matter, colour, odour, solubility, etc. all are the parameters of physical change. In a physical change, the composition or the chemical nature of matter does not change

Complete step by step answer:
During a physical change, the molecules are rearranged without changing the internal composition. A physical change has no effect on the chemical property of the matter.
Now, we will classify the given changes into physical and chemical change:
-Cutting of Trees: It is a physical change because in cutting the molecular structure of the trees does not change, only the size of the wood changes as it is cut into small pieces.
-Melting of butter in a pan: It is a physical change as melting only changes the shape of butter from solid to liquid. If you put it in the fridge it can return to its original shape again.
-Rusting of almirah: Rusting Is a chemical change as in rusting the metal gets oxidized by reacting with oxygen and water to form hydrated ferrous oxide which is called rust
-Boiling of water to form steam: It is a physical change as when you cool down the steam, it becomes water again.
-Passing of electric current through water and water breaking into hydrogen and oxygen gases: The molecules of water and the molecules of hydrogen and oxygen are two different molecules so when ${H_2}O$ is converted to ${H_2}$ and ${O_2}$, it is a chemical change.
-Dissolving common salt in water: It is a chemical change as when $NaCl$ is dissolved in water it breaks into $N{a^ + }$ and $C{l^ - }$ ions. The reactants are different from products.
-Making a fruit salad with raw fruits: It is a physical change as the molecular structure of the fruits does not change, only the size of the changes as it is cut into small pieces
-Burning of paper and wood: It is a chemical change as after burning paper becomes ash and both paper and ash have different chemical compositions.

Note:
Chemical changes are those changes in which the molecular composition is completely changed and a new product is formed. The changes that occur in a Chemical change are irreversible and permanent. Change in temperature, the formation of a precipitate, formation of bubbles are parameters of chemical change.