1) The Amazon rainforest produces more than 20% of the world's oxygen.

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

3) The word "bank" comes from the Italian word "banco," which means bench. In medieval Italy, bankers conducted their business on benches in the marketplace.

4) The first commercial mobile phone, the Motorola DynaTAC 8000X, was released in 1983 and weighed nearly 2 pounds.