Question

In caves, dripping groundwater containing calcium bicarbonate can form stalactites and stalagmites. When the water is exposed to air, some of the calcium bicarbonate turns into calcium carbonate, which gets deposited on the ground. What makes this process a chemical change? A new substance is formed in this process, which is an important clue to chemical change. A change in state is observed in this process, which is an important clue to chemical change. This process involves separation of dissolved substances, which is an an important clue to chemical change. This process involves dissolving substances together, which is an an important clue to chemical change. This process involves breaking and reshaping of substances, which is an an important clue to chemical change. NextReset

Answer 1

This is a chemical change because there is a new substance that was created and the new chemical can cause other chemical reaction to happen compared to the 1st state of chemical that was in the cave. Because the cave water was exposed to another environment, the calcium bicarbonate, which is also known as salt. When the cave's groundwater was exposed to a different environment the atom in the cave water rearranged and crystallized.  

Answer 2

Answer: The correct answer is a new substance is formed in this process, which is an important clue to chemical change.

Explanation:

Chemical change is defined as the process in which change in composition takes place. A new substance gets formed in this process. For Example: Formation of water molecule from hydrogen and oxygen gas.

A physical change is defined as the process in which change in shape, size and color takes place. No change in composition takes place as no new substance is getting formed. For Example: Melting of ice

We are given:

Sodium carbonate is being formed from sodium bicarbonate. The reaction for this follows:

$2NaHCO_3(s)\rightarrow Na_2CO_3(s)+CO_2(g)+H_2O(l)$

As, new substance which is sodium carbonate is getting formed. Thus, it is a chemical change.

Hence, the correct answer is a new substance is formed in this process, which is an important clue to chemical change.