Answer:
Q = 802.6 J
Step-by-step explanation:
Given data:
Specific heat capacity of water = 4.18 J/g.°C
Mass of water = 12 g
Initial temperature = 23°C
Final temperature = 39°C
Heat required = ?
Solution:
Formula: 
Q = m.c. ΔT 
Q = amount of heat absorbed or released 
m = mass of given substance 
c = specific heat capacity of substance 
ΔT = change in temperature 
ΔT = 39°C - 23°C
ΔT = 16 °C
Q = 12 g× 4.18 J/g.°C × 16 °C
Q = 802.6 J