question_answer

A mass of 50g of water in a closed vessel, with surroundings at a constant temperature takes 2 minutes to cool form \[{{30}^{0}}C\]to \[{{25}^{0}}C\]. A mass of 100g of another liquid in identical vessel with identical surroundings takes the same time to cool from \[{{30}^{0}}C\] to \[{{25}^{0}}C\]. The specific heat of the liquid is:                                   [JEE ONLINE 25-04-2013]

A)  \[2.0\operatorname{kc}\operatorname{a}\operatorname{l}/\operatorname{kg}\]     

B)       \[7.\operatorname{kc}\operatorname{a}\operatorname{l}/\operatorname{kg}\]

C) \[3\operatorname{kc}\operatorname{a}\operatorname{l}/\operatorname{kg}\]

D)                    \[0.5\operatorname{kc}\operatorname{a}\operatorname{l}/\operatorname{kg}\]

Correct Answer: D

Solution :

[d] As the surrounding is identical, vessel is identical time taken to cool both water and liquid (from 30°C to 25°C) is same 2 minutes, therefore

or,

(W= water equivalent of the vessel)

or,

Specific heat of liquid,