Apparatus: Glass bottle, baloon, hot water, etc. :
Procedure: Fix a balloon on the mouth of a glass bottle. Hold this bottle in hot water. What happens?

When hot water is poured in glass beaker.

Take a plastic boat and make a hole at this rear end. Inflate a balloon and fix it on the hole in the boat. Release the boat in water. What happens to the boat as the air in the balloon escapes slowly? Why?

Fomenting bottles, are used with hot water because

Bring ‘active dry yeast’ from the market. Mix a spoonful of yeast, two poonfuls sugar with «sufficient quantity of lukewarm water in a bottle. Fix a colourless, transparent balloon on the mouth of that bottle. Take a drop of the solution from the bottle on a glass slide, put a cover -slip over it and observe it under the compound microscope. Store the solution in the bottle carefully.

Bring 'active dry yeast' from the market. Mix a spoonful of yeast, two spoonful sugar with a sufficient quantity of lukewarm water in a bottle. Fix a colourless, transparent balloon on the mouth of that bottle. What changes do you observe after 10 minutes? Mix limewater with the gas accumulated in the balloon. Collect that lime water in a beaker and observe it. What do you notice?

Bring ‘active dry yeast’ from the market. Mix a spoonful of yeast, two poonfuls sugar with «sufficient quantity of lukewarm water in a bottle. Fix a colourless, transparent balloon on the mouth of that bottle. Find out how to use the solution prepared in the above experiment, to make bread. Follow the recipe and make the bread. Find out and note down the reasons why the dough rises and makes the bread spongy.

Apparatus: A beaker, potassium permaganate crystals, a burner, water, etc. : Procedure: Take some water in a beaker. Heat the beaker slowly on a gas burner. Drop a few crystals of potassium permaganate into the water. Now watch the water in the beaker carefully. What do you see?

Give scientific reasons: An ordinary glass bottle cracks when boiling water is poured into it.but a borosil glass bottle does not.

Give scientific reasons: Water droplets are seen on the outer surface of a cold drink bottle .