Question

which result is due to a chemical reaction?
a. water forms a gas.
b. dry ice forms a gas.
c. gas forms after mixing vinegar and baking soda.
d. salt and water form a mixture.

Explanation:

• Option A: Water forming a gas (e.g., boiling water) is a physical change (liquid - gas phase change).
• Option B: Dry ice (solid \(CO_2\)) forming a gas (\(CO_2\) gas) is a physical change (sublimation).
• Option C: When vinegar (\(CH_3COOH\)) and baking soda (\(NaHCO_3\)) are mixed, a chemical reaction occurs: \(CH_3COOH+NaHCO_3 = CH_3COONa + H_2O+CO_2\uparrow\). New substances (\(CH_3COONa\), \(H_2O\), \(CO_2\)) are formed.
• Option D: Salt and water forming a mixture is a physical process (dissolution).

Answer:

C. Gas forms after mixing vinegar and baking soda.