1. The baker wants to bake a spongy bread. Which of these should he use and why?

Answer: The baker should use yeast.
Yeast is a microorganism used in baking. When it acts on the sugar present in the dough, it releases carbon dioxide gas through the process of fermentation. This gas gets trapped in the dough, causing it to rise and creating small air pockets. As a result, the bread becomes soft, light, and spongy after baking.

2. Imagine a situation when your refrigerator is not working. How would you preserve the milk to be used after a few hours?

Answer: If the refrigerator is not working, a simple way to preserve milk for a few hours is by boiling it.

Boiling the milk kills or deactivates many of the microbes that cause spoilage. After boiling, the milk should be kept covered in a cool, dry place, away from direct sunlight. This method slows down microbial growth and helps keep the milk safe to consume for a few hours without refrigeration.