Question : Describethe experiment of Priestley.

1.	Question : Describethe experiment of Priestley.
Answer» Solution :Joseph Priestly (1733 - 1804) in 1770 performed series of experiments that reveated the essential role of air in the growth of green plants Priestley, discorvered oxygen in 1774. Priestley observed that a candle burning in a closed space - a BELL jar, soon gets extinguished (Figure a, b, c ,d) However a MOUSE would soon suffocatein a closed space. On the basis of these observations he CONCLUDED that a burning candle or an animal that breath the air, both somehow damage the air. Supplies deficit of air. But when he placed a mint plant in the same bell jar, he found that the mouse stayed alive and the candle continued to burm. Priestley hypothesised as follows : Plants restore to the air whatever BREATHING animals and burning candles remove.

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