1) Mountains are important water sources, as they capture and store precipitation, feeding rivers and supporting ecosystems downstream.

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

3) The fastest recorded serve in tennis was achieved by Sam Groth at 163.7 miles per hour (263.4 kilometers per hour) during a tournament in 2012.

4) Will Smith is an American actor, rapper, and producer known for his roles in films such as "Men in Black," "Independence Day," and "The Pursuit of Happyness." He has achieved success in both the music and film industries and has received numerous accolades for his work.