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ICSE Class 9 Answered

What is the aim of the experiment shown above? What is your observation after few hours for flask a and b? Name the chemical used to prevent the bacterial growth explain how the bacteria would interfere with the experiment? Why do we use thermos flasks specially for the experiment? Which is the control setup and why?
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Asked by Kanwaranita10 | 30 Jan, 2019, 08:12: PM
answered-by-expert Expert Answer

1. The aim of the experiment is to show that heat is evolved during respiration.

2. After few hours, the thermometer in flask A shows a higher reading, thus indicating a rise in temperature due to heat evolved by the germinating seeds. The thermometer in flask B does show any rise in temperature since no heat was evolved by the dead seeds.

3. Dilute formalin or carbolic acid is used to prevent bacterial growth in the flasks. If the bacteria grow, they would decay the seeds and thus, release heat which might interfere with the experimental observation.

4. A thermos flask prevents the loss or gain of heat energy due to conduction, convection, and radiation and thereby helps to obtain accurate observations.

5. The set-up in which the condition under study is missing is called the control. In flask B, the germinating seeds are missing and rest all other conditions are same. Dead seeds in flask B help to compare the heat evolved during the experiment. 
Answered by Sheetal Kolte | 31 Jan, 2019, 11:54: AM
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