Answer :
Yogurt contains living bacteria that are beneficial for our health. When a sealed container of yogurt is left for a very long time in a warm place, the bacteria in the yogurt continue to grow and multiply. This growth process produces gases such as carbon dioxide as a byproduct.
The warm temperature provides an ideal environment for the bacteria to thrive and increase their metabolic activity. As the bacteria consume the sugars in the yogurt to produce energy, they release gases. The accumulation of these gases inside the sealed container leads to an increase in pressure.
This increase in pressure causes the lid of the container to bulge upwards as the gases seek a way to escape. The bulging lid is a visible sign of the fermentation process happening inside the yogurt due to the activity of the living bacteria.
In summary, the bulging lid of a sealed container of yogurt left in a warm place for a long time is a result of the metabolic activity of the living bacteria present in the yogurt, leading to the production of gases that build up pressure inside the container.
