An insulated beaker contains 300 g of water at 30^o C . Water at 100^o C is added until the temperature of the mixture reaches 50^o C. The specific heat capacity of water is 4.2 J/(g^o C). How much water is added?

A 60 g
B 120 g
C 180 g
D 750 g

1 Answer
Mar 23, 2017

The answer is B

Explanation:

Let (m)g be the mass of water added.

The heat gained by the water at 30ºC=the heat lost by the water at 100ºC.

So,

300*cancel4.2*(50-30)=m*cancel4.2(100-50)

300*20=m*50

m=300*20/50=120g