1) The first successful human heart transplant was performed by Dr. Christiaan Barnard in 1967.

2) The blue whale is the largest animal to have ever existed, with an average length of about 82 feet (25 meters).

3) The word "pencil" contains two vowels: E and I.

4) Mountains are formed through various geological processes, including tectonic plate movements, volcanic activity, and erosion.