 Dear students, my name is Mohamad Asad and today we are going to perform an experiment named as fermentation of sugar. Fermentation of sugars can be performed by using different microorganisms like bacteria and fungus. But today we are going to perform sugar fermentation by using yeast. So before going into the detail of experiment, I would like to give you a brief introduction regarding fermentation, starting with the very basic definition of fermentation. Fermentation is basically the mass-culturing of microorganisms. It's a very old process which has been used by human being for a long time for the production of different products like bread, alcohol, wine, curd, pickle and many others. So let me introduce you with the chemical and apparatus which we will use in this experiment. We will use 4 glass flasks of 250 ml capacity. Then we will use sugar, yeast, distilled water, a glass-maring cylinder, tripod stand along with a spirit lamp, balloons and a lighter. So in the very first step, we will add 50 ml of distilled water in all these 4 flasks with the help of a maring cylinder. Now after adding the water in flask A, we will add 5 g of sugar which we have already weighed. In flask B, we will add 2.5 g of yeast. In flask C, we will add 2.5 g of yeast along with 5 g of sugar. And the same we will perform with flask D, that we will add 2.5 g of yeast and 5 g of sugars. Now after adding all these chemicals to the flask, we will take flask C and put it on a spirit lamp in order to boil this solution. We will gently shake the flask, we will boil this solution. So after boiling the solution present in flask C, we have also cooled it down on room temperature. We will put back flask C on its position and now we will cover all the flasks with the help of balloons. Now after covering these flasks with the help of balloons, we will incubate these flasks at least for 12 to 24 hours so that the reaction can complete. So after passing 12 hours, we will have such a situation. So before I explain the results, I will explain the principle behind the sugar fermentation. Basically when sugar and yeast react with each other, sugar get broken into CO2 and alcohol. CO2 tries to come out of the flask and it trapped into balloons. Now what happened with flask A? Basically in flask A, we had water and sugar. There was no yeast in flask A due to which reaction couldn't complete now. In flask B, we had yeast but we didn't add sugar due to which here again reaction remained incomplete. In flask C, we have sugar along with yeast but even then there had been no reaction observed. The reason behind is that you remember we have wild flask C during setting the assembly of this experiment. In flask D, you can see the balloon of flask D has been blown. The reason is in flask D, all the optimum conditions for the fermentation of sugar were maintained and when yeast break down the sugar as I have already told you, it makes alcohol and CO2. CO2 tried to come out of this flask and as we have covered this flask with the help of balloon that CO2 trapped in this balloon. This blowing of this balloon reflects that a complete reaction of fermentation has been occurred in this flask. In the end, students never forget to take basic precaution while performing any experiment like wearing of gloves and wearing of lab coat. Thank you.