Answer:
a: chemical change because the change cannot be reversed.
b: physical change because the action can be reversed.
c: chemical change.
d:chemical change.
any change that cannot be reversed is a chemical change and any change that can be reversed is a physical change.
What do you mean by unlock all of them? Please explain
<u>Answer:</u> The net ionic equation is written below.
<u>Explanation:</u>
Net ionic equation of any reaction does not include any spectator ions.
Spectator ions are defined as the ions which does not get involved in a chemical equation. They are found on both the sides of the chemical reaction when it is present in ionic form.
The chemical equation for the reaction of sodium carbonate and nickel (II) chloride is given as:

Ionic form of the above equation follows:

As, sodium and chloride ions are present on both the sides of the reaction. Thus, it will not be present in the net ionic equation and are spectator ions.
The net ionic equation for the above reaction follows:

Hence, the net ionic equation is written above.
<h3>Types of Osmosis</h3>
Osmosis is of two types:
Endosmosis– When a substance is placed in a hypotonic solution, the solvent molecules move inside the cell and the cell becomes turgid or undergoes deplasmolysis. This is known as endosmosis.
Exosmosis– When a substance is placed in a hypertonic solution, the solvent molecules move outside the cell and the cell becomes flaccid or undergoes plasmolysis. This is known as exosmosis.
<h2>
Answer:</h2>
In <u>Combination reaction</u>, two or more elements combined to form one compound of different properties.
- C(s) + O2(g) ⇢ CO2(g).
- H2(g) + O2(g) ⇢ H20(l).
In <u>Displacement reation</u>, the high reactive element displaces the low reactive element and formed compound of different properties.
- Fe(s) + CuSo4(aq) ⇢ FeSo4(aq) + Cu(s).
- AgNO3(aq) + Cu(s) ⇢ CuNO3(aq) + Ag(s).