1 Xiaohong found that there were three kinds of white solids in her kitchen sugar, salt, and soda

(1) Baking soda can react with hydrochloric acid to release carbon dioxide gas, so X is baking soda, and sodium chloride solution can react with silver nitrate solution to form silver chloride white precipitate, so Z is table salt, then Y is sugar

So the answer is: baking soda; Sugar: NaHCO3+HCl, NaCl+CO2+H2O; NaCl+AgNO3═NaNO3+AgCl↓

2) Lime water is alkaline, so drop add phenolphthalein solution to turn red, when blowing air into it, the reaction CO2 + Ca(OH)2 CaCO3 + H2O occurs, lime water becomes turbid, the alkalinity of the solution weakens, and the red color of the solution gradually fades

According to the calculation of the equal amount of carbon dioxide consumed each time, if the content of carbon dioxide in the classroom is x, then 24, the solution is: x

So the answer is: pumping location.

Number of pumps. The volume fraction of CO2 in the air.

Playground Classroom Because the content of carbon dioxide in the air is very low, the amount of calcium carbonate produced is very small, which is not enough to precipitate, so choose C

Therefore, the answer is: lime water becomes turbid, and the red color of the solution gradually fades CO2+Ca(OH)2 CaCO3+H2O; C