Limestone, chalk and marble are different forms of ______.

This question was previously asked in
SSC GD Constable (2022) Official Paper (Held On : 01 Feb 2023 Shift 1)
View all SSC GD Constable Papers >
  1. Calcium oxide
  2. Calcium carbonate
  3. Calcium hydroxide
  4. Calcium phosphate

Answer (Detailed Solution Below)

Option 2 : Calcium carbonate
Free
SSC GD General Knowledge and Awareness Mock Test
3.4 Lakh Users
20 Questions 40 Marks 10 Mins

Detailed Solution

Download Solution PDF

The correct answer is Calcium carbonate.

Key Points

  • Calcium carbonate and its forms: 
    • In nature, calcium carbonate occurs in the forms of chalk, limestone, and marble.
    •  Limestone, chalk, and marble are all sedimentary rocks that are composed mainly of calcium carbonate.
    •  Limestone is a sedimentary rock that forms from the accumulation of calcium carbonate shells and skeletons of marine organisms.
    • Chalk is a soft, white, porous rock that is made up of the microscopic remains of marine plankton.
    • Formation:
      • The skeletal remains of dead sea animals sink to the seabed. Over millions of years, layer build-up and pressure from the top layer changes the bottom layer into chalk. 
    • Earth movements due to earthquakes lift the layer of chalk to the Earth's surface. 
    • The earth's movements can also cause the layers to sink further. Thus, high pressure and heat cause the chalk to turn into much harder limestone. 
    • The limestone deposit may stay below the Earth for a longer time and due to higher pressure and temperature, the limestone turns to marble.

Additional Information

  • Calcium Oxide (CaO), commonly known as quicklime or burnt lime, is a widely used chemical compound.
    • It is a white, caustic, alkaline, crystalline solid at room temperature.
  • Calcium phosphate [Ca3(PO4)2] is fundamental to the formation of teeth and bone.
    • Calcium phosphate is a calcium salt of phosphoric acid. It is also known as Calcium phosphate tribasic or Tricalcium Phosphate.
  • Calcium Hydroxide [Ca(OH)2] is also known as Slaked lime.
    • It is a white powder or colourless crystal which is obtained when quicklime (calcium oxide) is mixed with water.
Latest SSC GD Constable Updates

Last updated on Jun 6, 2025

-> The SSC GD Notification 2026 will be released in October 2025 and the exam will be scheduled in the month of January and February 2026.

-> The SSC GD Merit List is expected to be released soon by the end of April 2025.

-> Previously SSC GD Vacancy was increased for Constable(GD) in CAPFs, SSF, Rifleman (GD) in Assam Rifles and Sepoy in NCB Examination, 2025. 

-> Now the total number of vacancy is 53,690. Previously, SSC GD 2025 Notification was released for 39481 Vacancies. 

-> The SSC GD Constable written exam was held on 4th, 5th, 6th, 7th, 10th, 11th, 12th, 13th, 17th, 18th, 19th, 20th, 21st and 25th February 2025. 

-> The selection process includes CBT, PET/PST, Medical Examination, and Document Verification.

-> The candidates who will be appearing for the 2025 cycle in the exam must attempt the SSC GD Constable Previous Year Papers. Also, attempt SSC GD Constable Mock Tests.  

-> UPSC Prelims Result 2025 Date Out soon @https://upsconline.nic.in/

More Chemistry in Everyday Life Questions

Get Free Access Now
Hot Links: online teen patti teen patti party real cash teen patti