Answer: 
Explanation:
Given
Mass of water is 
mass of ice is 
Latent heat of fusion 
The heat capacity of water is 
Suppose water is at
and it reaches to
to melt the ice
the heat released by water must be equivalent to heat absorbed by the ice

Answer:
The photoelectric effect is a phenomenon in which the photoelectrons are emitted from the metal when an incident electromagnetic wave hits the metal. The incident light should have a threshold frequency to meet the work function of the metal
I think phosphorus has the highest density at room temp.
2nd class leaver refers to such leaver in which load lies between effort and fulcrum.In a nut cracker too load is in between effort and fulcrum.Thus, nut cracker is a 2nd class leaver.......