200g
320g
400g
500g
Correct answer is D
Heat lost by hot water = Heat gained by cold water
M x 4200 x (100 - 60 = 0.4 x 4200 x (60 - 10)
4200m x 40 = 0.4 x 4200 x 50
40m = 0.4 x 50
m = \(\frac{0.4 \times 50}{40}\) = 0.5kg
= 500g