Physical and chemical changes are reversible and nonreversible changes. The release of carbon dioxide gas indicates a chemical change.
<h3>What is a chemical change?</h3>
A chemical change is a change in which a new substance is produced when the reactants react in the reaction mixture. The chemical produced cannot be reversed back to the reactants and hence, it is nonreversible.
The release of carbon dioxide is a chemical change as limestone and hydrochloric acid react with each other chemically and as a result, a new substance was formed.
Therefore, the production of carbon dioxide indicates a chemical change.
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Advantages of using tidal energy:
-Environment-friendly
-A highly predictable energy source
-High energy density
-Operational and maintenance costs are low
-An inexhaustible source of energy
Disadvantages of using tidal energy:
-High tidal power plant construction costs.
-Negative influence on marine life forms.
-Location limits.
-The variable intensity of sea waves.
Answer:
1s² 2s² 2p⁵
Explanation:
The elements of group 17 are called halogens. These are six elements Fluorine, Chlorine, Bromine, Iodine, Astatine. Halogens are very reactive these elements can not be found free in nature. Their chemical properties are resemble greatly with each other. As we move down the group in periodic table size of halogens increases that's way fluorine is smaller in size as compared to other halogens elements. Their boiling points also increases down the group which changes their physical states. i.e fluorine is gas while iodine is solid.
Properties of fluorine:
1. it is yellow in color.
2. it is flammable gas.
3. it is highly corrosive.
4. fluorine has pungent smell.
5. its reactions with all other elements are very vigorous except neon, oxygen, krypton and helium.
6. Its atomic number of 9.
7. its atomic mass is 18.99 amu.
Electronic configuration:
₉F = 1s² 2s² 2p⁵
