Questions

Water reabsorption by the renal tubules is harmonally controlled and it is a osmosis mechanism.

Same charges will repel each other and the charges that are different will attract each other.

Therefore the answer for What travels around the world but stays in one spot is STAMP or any other thing that acts as a stamp does.

Ex. the letter in the envelope etc...

Since, Several things have the possibility, but the word travel evokes that it would move. 

The amount of money you’ll get for a given amount of your country’s currency is based on internationally determined exchange rates. Exchange rates can be either fixed or floating. Fixed exchange rates use a standard, such as gold or another precious metal, and each unit of currency corresponds to a fixed quantity of that standard that should (theoretically) exist.

A nurse cannot diagnose a patient among the given options.