The law of conservation of momentum states that, if left alone, what happens to the total momentum of two interacting objects that make up a system?

would be false hope this out

neither accurate nor precise.

the answer is false. this is because for ice to melt, it requires latent heat of melting. latent heat means heat energy required to change phase without any increase in temperatures. therefore, the ice will take energy from the environment to melt hence atmospheric temperatures will reduce.

one "light year" is the distance that light travels, through vacuum, in one julian year.   that's 365.25 days, of 24 hours each.