Answer:
 19g
Step-by-step explanation:
Given parameters;
Amount of energy = 6346J 
Unknown: 
Mass of water frozen = ? 
Solution: 
This is a phase change and a latent heat was involve; 
 H = mL 
H is the quantity of heat 
m is the mass
L is the latent heat of fusion of water = 335J/g
So; 
 6346 = mass x 335 
 Mass = 19g