Change in state(from liquid to solid) and change in colour I believe.
Since power = work done/time, 60= work done/120, work done = 120*60 = 7200. So,work done = 7200N (Newton).
I'm not sure if you're supposed to convert the seconds to time.
Answer:
a.
b.
Explanation:
We are given that




a.We have to find the angle


b. We have to find the speed 
According to law of conservation of momentum



Force of gravity. Hope this is correct good luck!!