A group of cells doing the same job forms a tissue. A group of tissues working together forms an organ. Organs work in groups, too. A group of organs doing the same job is called a system.
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Answer:
Iodine. The reaction between hot iron and iodine vapor produces gray iron(II) iodide, and is much less vigorous. This reaction, the equation for which is given below, is difficult to carry out because he product is always contaminated with iodine. Iodine is only capable of oxidizing iron to the +2 oxidation state.
An atomic number is the number of protons that the atom of a particular element has.
For example, take carbon. Carbon has 6 protons. It's atomic number is 6.
