Misc: What is this short for - HiOAg?

Questions

------------- itself was formed by the activity of undersea volcanoes.?

------------- is the largest Western European country. Its area is slightly less than twice the size of Colorado.?

From the 1830s to 1960s, the Lehigh River in eastern -------------, was owned by the Lehigh Coal and Navigation Co., making it the only privately owned river in the United States.?

Grasshopper Glacier in ----------- was named for the grasshoppers that can still be seen frozen in the ice.?

-------------- is the world's oldest black republic. The major religion there is voodoo.?