The single most important chemical weathering agent is Carbon dioxide.
Weathering refers to the process that change the physical and chemical character of rock at or near the surface. Weathering has a dramatic impact on the composition of Earth's atmosphere. Chemical weathering removes carbon dioxide from the atmosphere, allowing it to be transformed into limestone and stored in the crust. Without chemical weathering, the elevated levels of carbon dioxide in the atmosphere would have long made Earth too hot to sustain life.
The correct answer is Cl.
Chlorine is a substance that's employed in industry and is present in a number of household goods. There are times when chlorine takes the form of toxic gas. Chlorine gas can be converted into a liquid by applying pressure and cooling so that it can be transported and stored. The term "oxidation number" refers to the number of electrons that an element's atom either loses or gains during the production of a compound. The charge that an atom seems to have when forming ionic connections with other heteroatoms is used to define an atom's oxidation number. Even if it develops a covalent bond, an atom with a higher electronegativity is given a negative oxidation state.
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If you mean the number of Significant Figures/Digits in 23.45, it would be 4. This is because every single non-zero digit is counted as a significant figure
