Limestone, chalk and marble are different forms of ______.
Show answer & explanation
Correct answer: D
Explanation
The correct answer is Option 4. i.e. Calcium carbonate.
Marble has a hard crystalline structure while Chalk is amorphous in nature. But limestone is a sedimentary rock which can occur in both crystalline and amorphous form.
- The main difference between limestone and marble is that limestone is a sedimentary rock, typically composed of calcium carbonate fossils, and marble is a metamorphic rock.
- Limestone forms when shells, sand, and mud are deposited at the bottom of oceans and lakes and over time solidify into rock.
- Marble forms when sedimentary limestone is heated and squeezed by natural rock-forming processes so that the grains recrystallize,
Decomposition: A substance breaks down to smaller species.
e.g. CaCO3(s) → CaO(s) + CO2(g)
Decomposition of limestone to calcium oxide (quicklime) and carbon dioxide on heating.