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Questions in chemistry

[Terjawab] What is the number of valence electrons in cadmium (Cd)? A. 1 B. 2 C. 10 D. 12

[Terjawab] 88. An element S has the proton number 18. The next element in the periodic table is an element T. Which statement is correct? A. Element T has one more electron in its outermost shell than element S. B. Element T has one more electron shell than element S. C. Element T is in the same group of the periodic table as element S. D. Element T is in the same period of the periodic table as element S. 89. Substance 'E' when reacts separately with zinc, sodium hydroxide and marble pieces, the respective products formed are hydrogen, sodium chloride and carbon dioxide. Identify the substance 'E'. A. An alkali B. An acid C. An element D. A salt 90. A yellow colored energy drink consists of a dissolved mixture of red and orange coloring agents. Suggest a suitable mean to separate these coloring agents. A. Distillation B. Evaporation C. Filtration D. Chromatography 91. What is the minimum age requirement of a person in Nepal to be eligible to vote in the national election? A. 16 years B. 18 years C. 19 years D. 21 years 92. The headquarter of World Trade Organization is located at London

[Terjawab] The atomic number of an element is defined as the number of a) electrons in the nucleus of an atom of the element b) neutrons in the nucleus of an atom of the element c) protons and neutrons in an atom of the element d) neutrons and electrons in an atom of element e) protons in the nucleus of an atom of the element

[Terjawab] Are the following ammonium compounds soluble in water? | Compound | Solubility | | :------- | :--------- | | $NH _4 OH$ | | | $NH _4 Cl$ | $\checkmark$ | | $( NH _4)_2 O$ | $\checkmark$ | | $NH _4 I$ | $\checkmark$ | | $NH _4 Br$ | $\checkmark$ | | $NH _4 NO _3$ | $\checkmark$

[Terjawab] Write the empirical formula of at least four binary ionic compounds that could be formed from the following ions: [tex]$Zn^{2+}, Al^{3+}, F^{-}, O^{2-}$[/tex]

[Terjawab] Calculate the change in internal energy (\Delta E) of a system that performs 158 kJ of work on its surroundings and loses 157 kJ of heat. Report your answer with the correct number of significant figures. Do not include units in your answer. Note that internal energy is given the symbol U in some textbooks.

[Terjawab] What would most likely be included in the "Analysis" section of a lab report? A. a discussion of any errors in the experimental data B. a list of the supplies that were used in conducting the experiment C. suggestions for new experiments based on the results D. a description of what the dependent and independent variables were

[Terjawab] The polyatomic ion in this compound is nitrate, [tex]$NO _3$[/tex]. What is the name of the compound? [tex]$Zn (NO _3)_2$[/tex] A. zinc (II) nitrate B. zinc nitrate C. zinc nitrite D. zinc peroxynitrate

[Terjawab] Verify your calculations for the rate. Are you reporting your data with the correct number of significant figures? | Concentration of iodide anion solution (mM) | 20.1 | 20.1 | | :------------------------------------------ | :---- | :---- | | Concentration of thiosulfate anion solution (mM) | 176.0 | 176.0 | | Concentration of hydrogen peroxide solution (mM) | 20.0 | | | Temperature of iodide anion solution (${ }^{\circ} C$ ) | 10.0 | | | Volume used of iodide anion solution ($I ^{-}$)(mL) | 1.0 | | | Volume used of hydrogen peroxide solution ($H _2 O _2$ )( $m _{1+1} y _{11}$ and $y _1$. | 8.8 | | | Time (s) | | | | Observations | | | | Initial concentration of iodide anion in the reaction (mM) | 47.6 | | | Initial concentration of thiosulfate anion in the reaction (mM) | 0.96 | |

[Terjawab] Fill in the systematic names of the following chemical compounds. Note: for compounds containing hydrogen, you may give the common name instead. | molecular formula | name of compound | | :---------------- | :--------------- | | $N _2 F_4$ | | | $NF _3$ | | | $P _4 S_3$ | | | $P _4 S_7$ | | | $H _2 O$ | |