How can a solid dissolved in water be separated from the water?

Which statement accurately describes the rock layers? layer 8 is older than layer 1. layer 3 is younger than layer 6. layer 4 and layer 10 are the same relative age. layer 2 and layer 9 are the same relative age.

The answer for #3 is c but i don't know why

It takes 945.kj/mol to break a nitrogen-nitrogen triple bond. calculate the maximum wavelength of light for which a nitrogen-nitrogen triple bond could be broken by absorbing a single photon.