According to the ingredients in the auxiliary materials, we can guess the bubble ingredients; Recall the inspection method of carbon dioxide; According to the composition of vitamin C, vitamin C is unstable to heat and reacts with water to deteriorate. Therefore, it should be preserved at low temperature and moisture-proof to prevent deterioration.

So, the answer is: My guess is that the composition of bubbles in my experimental scheme is: CO2；;

Cause: Sodium bicarbonate reacts with acidic substances in solution. Experimental steps. Experimental phenomenon. My conclusion: Put vitamin C effervescent tablets into water, and introduce the generated gas into clear limewater. Lime water turns into turbid gas. The reason of low CO2 temperature is that vitamin C is unstable to heat.

Moisture-proof reason: Vitamin C effervescent tablets react with water to deteriorate.