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ICSE Class 9 Answered

Two thermos flasks, one containing moist seeds and the other containing dry seeds were fitted with thermometers in cottonwool plugs as shown in the diagram. The initial temperature on both the thermometers was noted. After about 48 hours, the temperature in flask A was found to be much higher than that in flask B. (a) What does the given experiment aim?(b) Explain why a rise in temperature occurs in flask A.(c) If 5% formalin was not used after boiling the seeds, the temperature of flask B would have risen considerably. Explain.(d) Why were the flasks inverted?
Asked by Topperlearning User | 06 May, 2016, 06:48: AM
answered-by-expert Expert Answer

(a) The given experiment aims to show that heat is evolved during respiration.
(b) In flask A, moist seeds respire and produce heat, which increases the temperature of the flask.
(c) If 5% formalin was not used, bacteria would have grown on the dry seeds and respired anaerobically to produce little heat, thereby increasing the temperature of flask B.
(d) The flasks were inverted because in this position, the seeds completely surround the bulb of the thermometer and accurate reading can be noted.

Answered by | 06 May, 2016, 08:48: AM

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