1) The strongest natural material known to man is spider silk. It is stronger than steel and more flexible than nylon.

2) The Earth's core is hotter than the surface of the Sun.

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

4) The United Nations (UN) is an international organization founded in 1945 with the goal of promoting peace, security, and cooperation among nations through diplomatic and political means.