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Questions in chemistry

[Terjawab] 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

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

[Terjawab] 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]

[Terjawab] 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] | | |

[Terjawab] Classify the following compounds as normal, acid, double, basic, or complex salt. [tex]ZnSO _4, Na _2 Zn ( OH )_4, KHSO _4, Mg \left( NO _3\right)_2, K_4 Fe ( CN )_6, Mg ( OH ) NO _3[/tex], [tex]KAl \left( SO _4\right)_2 .12 H _2 O ,\left( NH _4\right)_2 Fe \left( SO _4\right)_2 .6 H _2 O , Zn ( OH ) Cl , NaHSO , NaHCO _n[/tex] [tex]FeCl _3, CH _3 COONa , Cu \left( NH _3\right)_4 SO _4, Na _2 CO _3[/tex].

[Terjawab] What is the heat of combustion of ethane, $C _2 H _6$, in kilojoules per mole of ethane? Enthalpies of formation can be found in the table of thermodynamic properties. $\\Delta H^*=1560$ $kJ /$ mol ethane

[Terjawab] What is the formula of this binary molecular compound? dinitrogen pentoxide A. ${ }_5 N_2 O$ B. $N _2 O 5$ C. $N (11) O ( V )$ D. $Ni _2 O _3$

[Terjawab] Fill in the name and empirical formula of each ionic compound that could be formed from the ions in the table. | cation | anion | empirical formula | name of compound | |---|---|---|---| | $Mn ^{2+}$ | $SO _3{ }^{2-}$ | | | | $K ^{+}$ | $MnO _4^{-}$ | | | | $Na ^{+}$ | $ClO _3^{-}$ | | |

[Terjawab] What should you do before working with compressed gas? A. Refer to the SDS for the gas and associated hazards B. Be trained in all elements of the hazard communication program C. Know your company's emergency procedures D. All of the choices are correct

[Terjawab] What is the atomic number of this element? [tex]\section*{${ }_{14}^{20} Si$}[/tex] 15 29 43 14