A lighted candle was placed in a bowl of water. We covered the candle with a glass.

A lighted candle was placed in a bowl of water. We covered the candle with a glass. After a while, the candle went out, and the water went under the glass. Explain the observed phenomenon.

All the oxygen that was under the glass burned out, instead of it carbon dioxide was released, which is less in volume. The candle does not burn without oxygen. There was a difference in pressure between the gas inside the glass and the pressure on the water in the plate due to the atmospheric pressure of the Earth. This difference gave rise to a force that pulled some of the water into the glass, like a pump.