Misc: In 1885 Congo Free State established by King ---------- of Belgium.?

Questions

a barnacle has the largest ---------- of any other animal in relation to its size?

a ---------- 's backbone is just as straight as a horse's?

a camel's backbone is just as straight as a ---------- 's?

a ---------- male reindeer is called a bull?

a castrated male ---------- is called a bull?