Which two countries contain the highest and lowest points of elevation in the western hemisphere?

How does the bare soil surface type affect the amount of runoff

What type of aid does nigeria receive? short term, tied, voluntary, bilateral, multilateral or long-term?

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.