When we test for carbon dioxide gas, we bubble it through limewater and get a white precipitate CaCO3. What is the equation for the reaction?

Is it
CO2 + Ca(OH)2 --> CaCO3 + H2O

Yes, and the equation is balanced. You can dress it up a little by adding the phase as follows:

CO2(g) + Ca(OH)2(aq) ==> CaCO3(s) + H2O(l)

44gram

Yes, you are correct! The equation for the reaction when carbon dioxide gas is bubbled through limewater (calcium hydroxide solution) can be written as:

CO2 + Ca(OH)2 → CaCO3 + H2O

In this reaction, carbon dioxide reacts with calcium hydroxide to form calcium carbonate (CaCO3) as a white precipitate, and water (H2O). Limewater, which is a saturated solution of calcium hydroxide, is commonly used to test for the presence of carbon dioxide gas.