Which situation is an indication that a chemical change has occurred? no color change occurs. a gas is formed. no heat is released. the temperature does not change.

The correct answer is B. A gas is formed

Explanation:

In chemistry, changes in substances or elements occur as a product of chemical reactions in which a substance reacts with others or decomposes. In any of these cases, the original substance or element changes into new or new substances, which does not occur in physical changes. This change in composition can be identified through different changes and signals that include a change in odor, color or temperature; the production of bubbles or gas; and the formation of a precipitate. According to this, the situation that is an indication of a chemical change is the formation of a gas, because only if the original substance has changed there would be a new substance such as a gas.

"you start with 15.67 g mgco3-xh2o, when heated and all the water is removed, you are left with 7.58 g mgco3 only.

therefore, you had 15.67 - 7.58 = 8.09g h2o  

moles of each :

7.58g mgco3 = ? moles = 7.58g / 83.4g/mole = 0.09moles  

8 09g h2o = ? moles = 8.09g / 18g/mole = 0.44moles  

molar ratio between the two by dividing both numbers by the smallest number :

0.09 / 0.09 = 1  

0.44 / 0.09 = 4.8  

mgco3-5h2o"