A liquid cools down from 70^oC to 60^oC in 5 minutes. The time taken to cool it from 60^oC to 50^oC will be

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Correct answer: C. (c) According to Newton's law of cooling, Rate of cooling ∝ mean temperature difference dQ_1 dt=k( 70+602- _0) =(65- _0) dQ_2 dt=k( 60+502- _0) =(55- _0) As dQ_2 dt< dQ_1 dt As rate of cooling is decreased, therefore liquid will take more than 5 min to cool from 60^ C to 50^ C.

$A liquid cools down from 7 0^{o} C to 6 0^{o} C in 5 minutes. The time taken to cool it from 6 0^{o} C to 5 0^{o} C will be$

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