Which mineral is never found freely in nature but is extracted from a chemical compound? a. coal b. salt c. gold d. silicon

D. Silicon

Explanation:

Silicon is very abundant in nature, in the entire universe it is the 7th most abundant, behind the following elements: hydrogen, helium, neon, oxygen, nitrogen and carbon. In the Earth's crust, it is the second largest (27.7%), second only to oxygen.

However, it is never found naturally in isolation, it is always combined with some other element, or chemical compound. For this reason, it was first prepared in the laboratory, in 1824, by the Swedish chemist Jöns Jacob Berzelius, by heating silicon tetrafluoride with potassium.

answer: 20 percent

the fish culture has become a developing commercial practice in developing countries which is already prominent in developed countries of the world. the major fish protein demand is being supplemented in developing countries is   fishing to meet the needs of the growing population. therefore, in some developing nations, the percentage of animal protein from fish in the diet can be as high as 20 percent.