Under which condition is light produced with respect to the hydrogen spectrum

Agricultural practices in the united states nearly led to the extinction of the peregrine falcon during the 1950s and 60s.

What are the answers for the following questions?

You have been tasked with sorting the rock samples shown into three categories, with two rocks in each category. what attribute would you use to sort these rocks? which rocks would be in each category? rocks: obsidian, coquina limestone, granite, soapstone, pumice, and gneiss.