Answer:
Temperature change is 12.5°C
Step-by-step explanation:
Let's apply the calorimetry formula for this problem
Q = c . m . ΔT
Where Q is heat (energy)
c is, the specific heat ( for water this value is 4.18 J/g°C) - A constant that is specific to each substance / compound that determines how easy it is to heat or cool that substance
m = mass
ΔT = T° change
20950 J = 4.18 J/°C . 400 g . ΔT
20950 J 7 (4.18 J/°C . 400 g) = ΔT → 12.5°C