Planet Earth has a complex structure:
– the solid inner core of the planet consists of two chemical elements – iron and nickel;
– outer liquid core – iron;
– the mantle consists of substances formed mainly by three chemical elements – aluminum, silicon and oxygen;
– the earth’s crust consists of oxygen (46%), silicon (28%), aluminum (8%), iron (5%), calcium (4%), sodium (3%), potassium (2%), magnesium (2 %) and other elements (2%).
Remember: The process of learning a person lasts a lifetime. The value of the same knowledge for different people may be different, it is determined by their individual characteristics and needs. Therefore, knowledge is always needed at any age and position.