1) The universe is estimated to be around 13.8 billion years old.

2) The Earth's core is primarily composed of iron and nickel and is as hot as the surface of the sun.

3) In African mythology, there is a rich tapestry of diverse beliefs and stories across the continent's many regions and cultures. It includes deities, spirits, and mythical creatures, with narratives often addressing themes of creation, ancestral heritage, and the forces of nature.

4) The word "oxygen" contains two vowels: O and E.