ستيب _ مجموعة هند

( 1)The main thrust of global conservation efforts today is to protect not just individual species but entire ecosystems. The goal is to preserve the natural interactions of many species. To that end, governments and conservation groups work to set aside land as parks and reserves. The United States has national parks, forests, and other protected areas. Marine sanctuaries are being created to protect coral reefs and marine mammals ( 2)The challenge is protecting areas that are large enough and that contain the right resources to protect biodiversity. To make sure that conservation efforts are concentrated in the most important places. conservation biologists have identified ecological hotspots '. An ecological hotspot is a place where significant numbers of species and habitats are in immediate danger of extinction. By identifying these areas, ecologists hope that scientists and governments can better target their efforts to save as many species as possible.

( 1)In an industrial society like the United States, the most important nonfuel resources are iron ore, aluminum ore, copper ore, and minerals containing nitrogen, phosphorus, and potassium used in fertilizers, a lot of energy is used in mining operations and the transportation of ore. To make the task of any physical extraction and transportation worthwhile, the ores must contain enough of the required compound or clement. Some lowgrade ore is not usable because of the cost of the mining process. ( 2)Materials extracted from the earth are processed by screening, separating, washing and grinding. Often, the useful element in an ore is in a chemical form that is not usable and must be changed to a desirable form. For instance, the aluminum in aluminum ore is in the form of aluminum ion. To be useful, the aluminum ion needs to be changed to aluminum metal.

Dmitri Mendeleyev has been hailed as the “genius who discovered the periodic table ”. However, Mendeleyev wasn’t even the third person to come up with the idea of the periodic table. That honor belongs to the German chemist and physician Lothar Meyer 1830-1895 (. Meyer wrote a popular book, The Modern theory of chemistry published in. While he was preparing the book, he noticed the relationship between the properties of a chemical element and its atomic weight.

السلام عليكم

In his paper, Dr. Smith expressed the conservative attitude of some of the Department's members towards the new program.