Iran
By area, the answer is Russia, who is 17,075,400 km2.
China has the largest population in Asia with over 1.4 billion people.
If you mean strictly in landmass, Canada. It is second only to Russia and encompasses 7% of the worlds land.
Russia is, geographically, the largest country in Europe, as well as the largest country in the world. Even if you only count the part of Russia that's in the European continent Russia is still, by far, the largest European country.
India
canada
China
Thailand
canada
The second most popular country in the world is Britain(First is America)
Iran
USA
The worlds largest population is Indonesia.http://islam.about.com/od/muslimcountries/a/population.htm
Africa is the second largest continent by both area and population.
Spain
Pakistan