Which country has the longest land border with Russia?

What is the name of the highest waterfall in South America? In which national park is the Russell Falls located? What is the height of the Kaieteur Falls? What is the largest country by total area in North America? What is the largest country by land area in Oceania? Which country is the second-largest by land area in Africa? What is the largest country by land area in Central Asia? What is the largest country by land area bordering the Arctic Ocean?