1) A single bolt of lightning can heat the surrounding air to temperatures five times hotter than the surface of the sun.

2) The national flower of Japan is the cherry blossom, which holds great cultural significance and is celebrated during the annual cherry blossom festivals.

3) The word "book" contains two vowels: O and O.

4) The hibiscus flower is commonly associated with tropical regions and is the national flower of several countries, including Malaysia, South Korea, and Haiti.