If a limestone piece is dipped in water, a bubble evolves. The bubbling is due to

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Q: 86 (CDS-I/2010)
If a limestone piece is dipped in water, a bubble evolves. The bubbling is due to

question_subject: 

Science

question_exam: 

CDS-I

stats: 

0,37,16,9,1,6,37

keywords: 

{'bubble evolves': [0, 0, 1, 0], 'bubbling': [0, 0, 1, 0], 'limestone piece': [0, 0, 1, 0], 'carbon dioxide': [2, 0, 5, 6], 'hydrogen': [0, 0, 1, 3], 'water': [65, 15, 80, 129], 'water vapour': [0, 0, 1, 2], 'oxygen': [3, 0, 1, 0]}

When a limestone piece is dipped in water, the bubbling that occurs is due to the release of carbon dioxide gas. Limestone is primarily composed of calcium carbonate (CaCO3), and when it reacts with water (H2O), it undergoes a chemical reaction known as carbonation. Carbonation results in the formation of carbonic acid (H2CO3), which is an unstable compound. As a result, carbonic acid rapidly decomposes into water and carbon dioxide gas.

The release of carbon dioxide gas is observed as the evolution of bubbles when the limestone piece is immersed in water. These bubbles are composed of carbon dioxide gas and rise to the surface of the water. It is important to note that the other options listed (hydrogen, oxygen, and water vapor) do not play a role in the bubbling observed when limestone is dipped in water.

Therefore, the correct answer is option 4: carbon dioxide.