KVPY SA Exam 2018 Question Paper

A coffee maker makes coffee by passing steam through a mixture of coffee powder, milk and water. If the steam is mixed at the rate of 50 g per minute in a mug containing 500 g of mixture, then it takes about ${\mathit{t}}_0$ seconds to make coffee at 70 ºC when the initial temperature of the mixture is 25 ºC. The value of ${\mathit{t}}_0$ is close to (ratio of latent heat of evaporation to specific heat of water is 540 ºC and specific heat of the mixture can be taken to be the same as that of water)