Hydrogen molecules are made up of only one element (hydrogen).
Water molecules, H₂O, are compounds because they are made up of more than one element, hydrogen and oxygen.
Here are some rules:
1. The oxidation state of a free element (uncombined element) is zero.2. For a simple (monatomic) ion, the oxidation state is equal to the net charge on the ion.3. Hydrogen has an oxidation state of +1 and oxygen has an oxidation state of −2 when they are present in most compounds.
The oxidation number of Fe in Fe(NO3)2 is +3.
A) would be correct.
The moon is right next to Earth.
Earth orbits around the sun.
Our solar system is at the edge of the Milky Way. So the edge of the Milky Way would be nearer than the center.
Radioactive isotopes eventually decay, or disintegrate, to harmless materials. Some isotopes decay in hours or even minutes, but others decay very slowly. Strontium-90 and cesium-137 have half-lives of about 30 years (half the radioactivity will decay in 30 years). <u>Plutonium-239 has a half-life of 24,000 years.</u>
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<h3>What is radioactive decay? </h3>
Radioactive decay is the emission of energy in the form of ionizing radiation. The ionizing radiation that is emitted can include alpha particles, beta particles and/or gamma rays. Radioactive decay occurs in unbalanced atoms called radionuclides.
Elements in the periodic table can take on several forms. Some of these forms are stable; other forms are unstable. Typically, the most stable form of an element is the most common in nature. However, all elements have an unstable form. Unstable forms emit ionizing radiation and are radioactive. There are some elements with no stable form that are always radioactive, such as uranium. Elements that emit ionizing radiation are called radionuclides.
Learn more about Radioactive decay
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Answer:
it will A. d. e. f option above