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Questions in chemistry

[Done] What is phosphorescence? A. A material that absorbs lots of light B. A material that we C. A material that

[Done] How many moles of copper (II) sulphate are present in the 100cm3 solution?

[Done] What is the noble gas electron configuration for calcium, Ca? A. [Ar] 4s^2 3d^5 B. [Ar] 4s^2 3d^{10} C. [Ar] 4s^2 D. [Ar] 4s^2 3d^{10} 4p^3

[Done] How did Moseley establish a more accurate periodic table? A. by arranging the elements according to atomic mass instead of atomic number B. by arranging the elements according to atomic number instead of atomic mass C. by arranging the elements into horizontal periods D. by arranging the elements into vertical groups

[Done] What are the reactants in this chemical reaction? Silicon dioxide plus hydrofluoric acid produces silicon tetrafluoride and water. A. [tex]$SiO _2+ HF$[/tex] B. [tex]$SiF _4+ SiO _2$[/tex] C. [tex]$HF + H _2 O$[/tex] D. [tex]$SiF _4+ H _2 O$[/tex]

[Done] Fill in the name and empirical formula of each ionic compound that could be formed from the ions. | Some ionic compounds | | --- | --- | --- | --- | | cation | anion | empirical formula | name of compound | | [tex]Cr ^{2+}[/tex] | [tex]SO _4^{2-}[/tex] | | | | [tex]Mg ^{2+}[/tex] | [tex]C _2 H _3 O _2^{-}[/tex] | | | | [tex]Na ^{+}[/tex] | [tex]IO _2^{-}[/tex] | | |

[Done] Based on the electron configuration, how many valence electrons are in cesium, Cs? $1 s^2 2 s^2 2 p^6 3 s^2 3 p^6 4 s^2 3 d^{10} 4 p^6 5 s^2 4 d^{10} 5 p^6 6 s^1$ A. 6 B. 1 C. 55 D. 18

[Done] Which element is a halogen? A. argon B. bromine C. calcium D. lithium.

[Done] What are the products in this chemical reaction? silicon dioxide plus hydrofluoric acid produces silicon tetrafluoride and water. [tex] \begin{array}{l} SiF_4+H_2 O \\ SiF_4+SiO_2 \\ SiO_2+HF \\ HF+H_2 O \end{array} [/tex]

[Done] Fill in the name and empirical formula of each ionic compound that could be formed from the ions in this table: | cation | anion | empirical formula | name of compound | |---|---|---|---| | [tex]Mg ^{2+}[/tex] | [tex]SO _4^{2-}[/tex] | | | | [tex]Pb ^{2+}[/tex] | [tex]MnO _4[/tex] | | | | [tex]K ^{+}[/tex] | [tex]PO _3^{3-}[/tex] | | |