Using the most likely definitions of those words, Iceland is none of those things, as China, for example, is older, Kiribati, for example, is lower, and Montenegro, for example, is younger. Using other interpretations of the meanings of oldest, youngest, and lowest, it is possible that Iceland is the youngest country in the world in the sense that the landmass that the country occupies is geologically younger that any other, having formed volcanically more recently than any other landmass constituting an entire country. Using age of population, it is not the youngest or oldest, as the youngest populations are in Africa, and a number of European countries have older populations. Ultimately, perhaps what you are thinking of is the fact that Iceland has the oldest parliament in the world, the "Althing", founded in 930AD, and may be (loosely or arguably) called the oldest democracy in the world (still extant).
It is none of the above. China is older, Kubrati is lower, and montenegro is younger.
Iceland
Iceland.
Iceland, Alþingi
The oldest democratic country is generally considered to be Iceland, with its parliamentary government dating back to the year 930.
states that the lowest rock in layers is the oldest and the highest is the youngest rock layer
The oldest or youngest what?
According to the law of superposition, the lowest layer in a cross section of rock is the oldest, as sedimentary rocks are typically laid down in sequence with the oldest rocks at the bottom and the youngest at the top.
He is the oldest.
oldest generation up, youngest down
Who are the oldest and youngest players to complete in the Iditarod?
australias oldest and youngest capital cities