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Questions in chemistry

[Free] Which substances have [tex]$\Delta H_{ f }=0 kJ / mol$[/tex] by definition? Select all that apply. [tex]$O _2(g)$[/tex] [tex]$N ( g )$[/tex] [tex]$H _2 O ( l )$[/tex] [tex]$Br _2( I )$[/tex] Fe(s) He(g)

[Free] Compound Table Activity Find 10 items at home that you think are either elements or compounds. In the first column titled "Item Picture", write or draw the item (e.g., salt, water, iron, oxygen, etc.). In the second column titled "Element or Compound?", identify whether the item is an element (like gold, oxygen, iron) or a compound (like water, sugar, vinegar). In the third column titled "Reason", explain why you identified the item as an element or compound. Example: Water - Compound – It is made of hydrogen and oxygen. Iron - Element - It is made of only one type of atom.

[Free] Use the electronegativity values given to answer the following: Electronegativity values: [tex]$C =2.5, H =2.1, N=3.0, O =3.5, Cl =3.0$[/tex] For each bond below: a) Determine the electronegativity difference b) State the bond type (ionic, polar covalent, or non-polar covalent) c) Predict whether the molecule is polar or non-polar (assume correct geometry) | Molecule | [tex]$\Delta EN$[/tex] | Bond Type | Molecule Polarity | |----------|------------------|-----------|-------------------| | [tex]$H - Cl$[/tex] | | | | | [tex]$C - H$[/tex] | | | | | [tex]$N - H$[/tex] | | | | | [tex]$O - H$[/tex] | | | |

[Free] Use the periodic table to complete this equation that represents nuclear fission processes. ${ }_{92}^{275} U+{ }_0^1 n \rightarrow{ }_{50}^{139} Ba+{ }_8^1 C+3{ }_0^1 n$ A: $\square$ B: $\square$ C: $\square$

[Free] Select all the correct locations on the image. Which elements are diatomic? \begin{tabular}{|c|c|} \hline 1 & \\ \hline H & \\ \hline 3 & 4 \\ Li & Be \\ \hline 11 & 12 \\ Na & Mg \\ \hline 19 & 20 \\ K & Ca \\ \hline 37 & 38 \\ Rb & Sr \\ \hline 55 & 56 \\ Cs & Ba \\ \hline 87 & 88 \\ Fr & Ra \\ \hline \end{tabular} \begin{tabular}{|c|c|c|c|c|c|} \multicolumn{7}{c|}{} & \multicolumn{1}{c|}{4} & \multicolumn{1}{c|}{ He } \\ \hline B & 6 & 7 & 8 & 9 & 10 \\ B & C & N & O & F & Ne \\ \hline 13 & 14 & 15 & 16 & 17 & 18 \\ Al & Si & P & S & Cl & Ar \\ \hline 31 & 32 & 33 & 34 & 35 & 36 \\ Ga & Ge & As & Se & Br & Kr \\ \hline 49 & 50 & 51 & 52 & 53 & 54 \\ In & Sn & Sb & Te & I & Xe \\ \hline 81 & 82 & 83 & 84 & 85 & 86 \\ TI & Pb & Bi & Po & At & Rn \\ \hline 113 & 114 & 115 & 116 & 117 & 118 \\ Nh & FI & Mc & Lv & Ts & Og \\ \hline \end{tabular}

[Free] 4. Define the following in one sentence or two: (a) Compound (b) Crystallization (c) Decantation (d) Distillation (e) Filtration 5. Match the type of mixture in Column A with the correct examples in Column B Column A (a) Gas in gas (b) Gas in liquid (c) Liquid in liquid (d) Solid in liquid (e) Solid in solid (f) Solid in gas Column B (i) Smoke (ii) Soil (iii) Sea water (iv) Lemon juice in water (v) Aerated water (soda) (vi) Air

[Free] List 5 objects/materials found in the kitchen, bathroom, living room, and classroom. Classify each material as SOLID, LIQUID, or GAS. | Place (Designated area to visit) | Name of Matter | Classification | |---|---|---| | KITCHEN | 1. | | | | 2. | | | | 3. | | | | 4. | | | | 5. | | | BATHROOM | 1. | | | | 2. | | | | 3. | | | | 4. | | | | 5. | | | LIVING ROOM | 1. | | | | 2. | | | | 3. | | | | 4. | | | | 5. | | | CLASSROOM | 1. | | | | 2. | | | | 3. | | | | 4. | | | | 5. | |

[Free] What else is produced during the replacement reaction of silver nitrate and potassium sulfate? [tex]2 AgNO_3+K_2 SO_4 \rightarrow Ag_2 SO_4 +[/tex] A. [tex]KNO _3[/tex] B. [tex]2 KNO _3[/tex] C. [tex]K _2[/tex] D. [tex]2 AgNO _3[/tex]

[Free] Therefore, who can describe the properties of solids, liquids, and gases in terms of shape and volume?

[Free] Select the correct answer from each drop-down menu. What effect does a decrease in the concentration of nitrogen monoxide (NO) gas have on the rate of reaction in this chemical equation? [tex]2 NO(g)+H_2(g) \rightarrow N_2 O(g)+H_2 O(g)[/tex] A decrease in the concentration of nitrogen monoxide [dropdown] between NO and [tex]H _2[/tex] molecules. The rate of the forward reaction then [dropdown].