In which country is most of the Rub' al Khali (Empty Quarter) located?

What is the highest mountain in Iceland? In which country is most of the Namib Desert located? In which country is most of the Negev Desert located? In which country is most of the Simpson Desert located? In which country is most of the Thar Desert located? In which country is Lake Como located? In which country is Lake Garda located? In which country is Lake Ladoga located?