Why should we put a glass on candles for experiments and why should we put candles on sand trays ?​

1, you should use candles for experiments because, You created an area of low pressure! When the experiment is run you can see tiny bubbles escaping under the glass which shows that the increased air pressure from the heated air as the candle burns. Once the candle runs out of oxygen, the candle burns out and the remaining air inside cools down.

2. you should put candles on sand trays, Pour layers of sand into a glass vase, alternating colors with each layer. For a more interesting look, try uneven layers in various heights. Keep layering sand until you're a few inches from the top of the vase. Place your votive candle in the center of the sand.

Explanation:

its scientific proven

c is the answer because when something is left after something evaporates that shows the chemical change.

the answer to this question is 3.