1.

The image shows a page from a textbook in Russian, focusing on water (H₂O) and its properties as a compound. Here are some key points:

1. About Water: It details that water is a compound made of hydrogen and oxygen.
2. Elementary Composition: It consists of two hydrogen atoms and one oxygen atom, forming H₂O.
3. Physical and Chemical Properties: It describes water's physical and chemical characteristics.
4. Common Name: The common name for H₂O is given as "water."
5. Verification of Knowledge: It provides a task for the reader to verify their knowledge, such as determining what H₂O represents and understanding the properties of water.

Additionally, the text discusses the characteristics of oxygen and its concentration.