A calorimeter of water equivalent `6g` has water of mass `64g` up to a certain volume An other identical calorimeter has liquid of mass 5g and specific heat `0.6 calg^(@)C` upto same level If both pf them cool in the same surroundings through same range of temperature and the time taken for the water to cool is `140s` the time taken for the liquid to cool is .

Options

A. `72 s`
B. `140s`
C. `36s`
D. `120s`

Answer

A

Explanation

From Newton's law cooling `(d theta)/(dt) prop (1)/(ms) rArr t prop ms, (m_(1)s_(1)+m_(2)s_(2))/(t_(1))=(m_(1)s_(1)+m_(3)s_(3))/(t_(2))` .