Answer:
500 g
Explanation:
m = Mass of water
c = Specific heat of water = [tex]1\ \text{cal/g}^{\circ}\text{C}[/tex]
[tex]\Delta T[/tex] = Temperature difference = [tex]100-20=80^{\circ}\text{C}[/tex]
Q = Heat added = 40000 cal
Heat is given by
[tex]Q=mc\Delta T\\\Rightarrow m=\dfrac{Q}{c\Delta T}\\\Rightarrow m=\dfrac{40000}{1\times 80}\\\Rightarrow m=500\ \text{g}[/tex]
The mass of water is 500 g.