化學
化學反應、化學計量、分子結構與元素性質。
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an advertisement for a commercial hand warmer claims that the hand warm…
A. The advertisement’s claim is inaccurate because heat flowing from the hands to the warmer would only happen if the chemical reaction was endothermic, which would cause the hand…
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which balanced chemical equation does the particle diagram represent? r…
A. \( 3\text{CH}_4 + 6\text{O}_2 ightarrow 3\text{CO}_2 + 6\text{H}_2\text{O} \)
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when pellets of naoh(s) are added to a flask of water, it is observed t…
C. It is an exothermic process because heat energy is absorbed by the water as the $\ce{NaOH}(s)$ dissolves in it.
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hcl(aq) + nh₃(aq) → nh₄⁺(aq) + cl⁻(aq) the chemical reaction between hc…
C. It is an exothermic process, because energy is released by the reaction and is gained by the reaction mixture.
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for each row in the table below, decide whether the pair of elements wi…
To solve this, we analyze each element pair: ### Row 1: Hydrogen (H) & Chlorine (Cl) - **Molecular Compound?** Yes (both nonmetals, form covalent bonds). - **Formula (fewest atoms…
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draw all the structural isomers for the molecular formula c₃h₇br. draw …
1. 1-Bromopropane: ``` H H H | | | H-C-C-C-Br | | | H H H ``` 2. 2-Bromopropane: ``` H H H | | | H-C-C-C-H | | | H Br H ```
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which of these are illegal or scam activities? check all that apply. □ …
- running a pyramid scheme - threatening to harm property - downloading a virus - hacking a computer
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which image depicts the correct particle model for the products of the …
The third image (with molecules each having two black spheres and one white sphere, arranged as \( \ce{H_2O} \) models)
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complete the table below by writing the symbols for the cation and anio…
The completed table is as shown above with cations and anions: - \( \text{MnCl}_2 \): Cation \( \boldsymbol{\text{Mn}^{2+}} \), Anion \( \boldsymbol{\text{Cl}^-} \) - \( \text{Mn}…
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complete the table below by writing the symbols for the cation and anio…
| Ionic Compound | Cation | Anion | |----------------|--------------|--------------| | \( \ce{NaCl} \) | \( \ce{Na^+} \) | \( \ce{Cl^-} \) | | \( \ce{MnCl2} \) | \( \ce{Mn^{2+}} \…
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complete the table below by writing the symbols for the cation and anio…
| Ionic Compound | Cation | Anion | | ---- | ---- | ---- | | \(NaCl\) | \(Na^+\) | \(Cl^-\) | | \(VBr_3\) | \(V^{3+}\) | \(Br^-\) | | \(CrF_3\) | \(Cr^{3+}\) | \(F^-\) | | \(CoI_2…
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a sample of x is carefully weighed and put inside a vented flask. water…
First experiment: physical Second experiment: physical
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in each case, decide whether the property measured was a chemical or ph…
chemical ### For the second experiment (D):
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heated until oxygen gas starts being produced. after no more oxygen gas…
chemical ### Second Experiment (Radio - Frequency Current Through Sample)
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experiments were done on a certain pure substance x to determine some o…
chemical ### For the second experiment (E):
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fill in the systematic names of the following chemical compounds. note:…
To solve the problem of naming the given molecular compounds, we follow the rules for naming molecular (covalent) compounds, which involves using prefixes to indicate the number o…
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based on the particle model, which equation best accounts for the chemi…
B. \(N_2 + 3H_2 ightarrow2NH_3\)
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based on the particle model, which reactant is the limiting reactant? x…
element X
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based on the particle model, which equation best accounts for the chemi…
C. C + 2H₂ → CH₄ (Wait, the options are: first option: C + O₂ → CO₂, second: 4C + 6O₂ → 4CO₂ + 2O₂, third: C + 2H₂ → CH₄. So the correct option is the third one, which is C + 2H₂ …
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question 4 of 6 4 what evidence does the author use to support the gian…
A. Earth and Moon rocks are almost chemically identical C. The Moon is about one-quarter of Earth's diameter
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earth and moon rocks are almost chemically identical the moons size is …
- Earth and Moon rocks are almost chemically identical - The Moon is about one-quarter of Earth's diameter
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why is there a change in energy during chemical reactions? (1 point) ch…
Energy is released by the formation of chemical bonds, and energy is absorbed when the bonds are broken.
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a cold pack is snapped, and the chemical reaction causes the pack to fe…
This is an endothermic reaction because the system took energy from the surroundings.
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which statement is true of energy in reactants during an endothermic re…
The energy found in the reactants remains in the system, and the reactants also take energy from the surroundings.
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a candle slowly burns until the last bit of wax and wick are gone. the …
C. In the air, only the oxygen is part of the system.
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which quantity will always have a negative value? (1 point) the change …
the change in energy in a system during an exothermic reaction
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unit 5 sections a & b test review part a. naming ionic and molecular co…
| Chemical Formula | Ionic or Molecular Compound? | Chemical Name | |------------------|-------------------------------|---------------| | $\text{P}_5\text{Cl}_{10}$ | Molecular |…
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how did you pick the air molecules in the previous question? * ○ they h…
They had the same types atoms as the food molecules.
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write the chemical symbol for an element belonging to each of the eleme…
For the "noble gas" family, an example element's chemical symbol is $\boldsymbol{He}$ (or $Ne$, $Ar$, etc.). For the "alkaline earth" family, an example element's chemical symbol …
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write the name of the element family to which each of the elements in t…
For fluorine: Halogens For magnesium: Alkaline Earth Metals
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how does parent material influence soil formation? a. it provides the i…
a. It provides the initial material from which soil is formed b. The breakdown of rocks into smaller particles
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are three sets of sketches below, showing the same pure molecular compo…
To solve this, we analyze the states of matter based on the melting and boiling points of \( \text{SO}_2 \) (melting point \( -72.0^\circ\text{C} \), boiling point \( -10.0^\circ\…
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11. calcium hydroxide + phosphoric acid → water + calcium phosphate 12.…
11. $3\text{Ca(OH)}_2 + 2\text{H}_3\text{PO}_4 ightarrow 6\text{H}_2\text{O} + \text{Ca}_3(\text{PO}_4)_2$ 12. $\text{BaCl}_2 + \text{Na}_2\text{CO}_3 ightarrow \text{BaCO}_3 + 2\…
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in the spectrophotometry lab experiment, you constructed a calibration …
The calibration curve was used to determine the molar absorptivity, $\epsilon$, which was the slope of the line.
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in the spectrophotometry lab experiment, you calibrated a spectrophotom…
Solutions with higher concentrations have lower absorbances, while more dilute solutions have higher absorbances.
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ws: molecular and empirical formulas write the molecular formulas of th…
s: 1) Molecular Formula: \( \boldsymbol{C_4H_8O_2} \) (or \( C_4O_2H_8 \)) 2) Molecular Formula: \( \boldsymbol{C_6H_{12}O_3} \) (assuming empirical \( C_2H_4O \)) 3) Molecular Fo…
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use with textbook pages 256-267. types of chemical reactions—word equat…
1. S; $\ce{Mg + S -> MgS}$ 2. N; $\ce{2KOH + H2SO4 -> 2H2O + K2SO4}$ 3. SR; $\ce{Cl2 + 2KI -> 2KCl + I2}$ 4. DR; $\ce{AlCl3 + 3NaOH -> Al(OH)3↓ + 3NaCl}$ 5. D; $\ce{2PbO -> 2Pb + …
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using the calibration curve, calculate the molar concentration for a so…
The molar concentration is approximately \(\boldsymbol{0.519}\) M.
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what element is designated by the orbital diagram below? (note that cor…
Nickel (Ni)
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which electron configuration violates hunds rule? answer: a $\\text{he}…
D. $[\text{He}]2\text{s}^22\text{p}_x^22\text{p}_y^2$
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use the calibration curve to answer the following questions. part: 0 / …
y - axis ### For the second question (Is concentration graphed on the x - axis or the y - axis?):
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decide whether each sketch shows a sample of an element, a compound, or…
s: - Substance Z: element - Substance X: compound - Substance T: mixture - Substance Y: mixture
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the mechanism used by a person to vape or inhale flavors, chemicals, or…
A. NDS - E-Cigarette
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empirical formula & molecular formula ws remember: percent to mass, mas…
The empirical formula is \( \boldsymbol{C_3H_6O_2} \) (Wait, wait, let's check the calculations again. Wait, maybe I made a mistake in the oxygen mass. Wait, 100 - 48.38 - 8.12 = …
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experiment: measurements post lab questions 1) perform the indicated ma…
### Question 1: Mathematical Operations with Uncertainty #### Part 1: \( 7.700 \times 2.1 \) # Explanation: ## Step 1: Perform the multiplication \( 7.700 \times 2.1 = 16.17 \) ##…
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empirical formula & molecular formula ws remember: percent to mass, mas…
The empirical formula is \( \text{C}_3\text{H}_6\text{O}_2 \)
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problem 9 of 56 what element is designated by the orbital diagram below…
Nitrogen (N)
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empirical formula & molecular formula ws remember: percent to mass, mas…
$\ce{C3H6O2}$ ### Problem 2
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empirical formula & molecular formula ws remember: percent to mass, mas…
\(C_3H_6O_2\) ### Problem 2
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there are four substances (substance a, substance b, substance c, subst…
To solve this, we analyze each substance: ### Substance B - **Step 1: Identify particle type** Substance B has only one type of atom (silver - colored spheres) and each particle i…
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find the percent compositions of all of the elements in the following c…
s: 1) $Cu$: $\approx 28.45\%$, $Br$: $\approx 71.55\%$ 2) $Na$: $\approx 57.48\%$, $O$: $40.00\%$, $H$: $\approx 2.52\%$ 3) $N$: $\approx 41.11\%$, $H$: $\approx 11.83\%$, $S$: $\…
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question: why is the average atomic mass on the periodic table often a …
A. Because it is a weighted average of all naturally occurring isotopes
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question. can you measure the mass of a single atom with a normal labor…
D. No, atoms are too small to weigh individually with standard lab equipment
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question: what happens to the average atomic mass when the number of he…
B. It increases
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question 7 how does the simulation model average atomic mass? ○ it show…
C. It allows users to change the number of isotopes and measure their masses
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question # 6 by krystal wellmann in the boron simulation, if there are …
78%
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loudon | parise seventh edition consider the incomplete structure. add …
-1 (corresponding to the option $\boldsymbol{-1}$) The formal charge on the oxygen atom is $-1$, and all other atoms have a formal charge of $0$.
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the skeleton of the bicarbonate ion, hco₃⁻, is shown here. draw the com…
The correct Lewis structure is: ``` .. O = C - O⁻ | .. O-H .. ``` (Or with spatial arrangement: Carbon is central, double-bonded to one O (with 2 lone pairs), single-bonded to one…
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question. what are the two isotopes used in the boron simulation? boron…
A. Boron - 10 and Boron - 11
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question: which formula correctly calculates average atomic mass? (abun…
(abundance × mass) for each isotope, then add them together
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why must we use percent abundance when calculating average atomic mass?…
C. To give more influence to isotopes that occur more frequently
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question. what is average atomic mass? the number of protons in the mos…
C. The weighted average of all isotopes of an element based on their percent abundance
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which statement is the best example of a valid hypothesis? people shoul…
B. If I add substance X, then it will lower the temperature at which water freezes.
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which chemistry advancement has made the greatest impact on human lives…
B. genetically modified crops increasing the food supply
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in a sample of hydrogen iodide, what intermolecular forces exist in add…
dipole - dipole forces (the option with "dipole - dipole forces")
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calculate the amount of heat needed to boil 15.5 g of methanol (ch₃oh).…
17.03 kJ (Option: 17.03 kJ)
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determine the phase change that carbon dioxide undergoes as temperature…
sublimation
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multiple choice which term best describes the contemporary public view …
ambivalent
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which of the following pure substances has the strongest dispersion for…
\(C_8H_{18}\)
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the intermolecular interactions between pentane ($c_5h_{12}$) molecules…
London dispersion forces.
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question #5 multiple choice how does todays food market compare to the …
A. Today's food market is dominated by chain stores.
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which of the following pairs of compounds does not have the one of high…
HCl, H₂S
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which of the following pairs of compounds does not have the one of high…
# Brief Explanations: 1. For \( \ce{MgO} \) and \( \ce{NaCl} \): Both are ionic compounds. Lattice energy depends on ion charge and size. \( \ce{Mg^{2+}} \) and \( \ce{O^{2-}} \) …
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what kind of intermolecular forces act between a hydrogen molecule and …
D. Dispersion forces
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which of the following will not participate in hydrogen bonding?\ \\(\\…
\( \boldsymbol{\text{CH}_3\text{F}} \) (the option with \( \text{CH}_3\text{F} \))
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which substance will exhibit hydrogen bonding between molecules? ○ $\\c…
\( \boldsymbol{\text{CH}_3\text{CH}_2\text{-OH}} \) (the option with the structure \( \text{CH}_3\text{CH}_2\text{-OH} \))
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whats the best definition of chemistry? the study of matter and the cha…
A. The study of matter and the changes it undergoes ### Question 2
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which sentence uses this meaning of vacuum? vacuum noun a space that is…
The chemist pumped the air out of the small glass chamber and turned it into a vacuum.
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name class date determine what is happening in each picture and write w…
1a. An ice cube melts in water 1b. Physical Change --- 2a. Two clear liquids form a solid precipitate 2b. Chemical Change --- 3a. A white powder dissolves in a clear liquid 3b. Ph…
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classifying matter practice directions: label each picture with a label…
1. 2) Compound 2. 3) Mixture of Elements 3. 5) A mix of elements and compounds 4. 5) A mix of elements and compounds 5. 1) Element 6. 4) Mixture of Compounds 7. 3) Mixture of Elem…
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select the correct answer. a chemist is performing an experiment by obs…
D. from hour 0 to hour 5
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can you explain it? how could the water in a dinosaur’s drink end up in…
1. The water likely went through the water cycle: it evaporated from a large water body into vapor, condensed into clouds, fell as precipitation, entered a water source (reservoir…
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select the correct answer from each drop - down menu. read the excerpt …
1. First dropdown: neoclassical 2. Second dropdown: heroic couplets 3. Third dropdown: elevated formal
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is the phrase in bold a direct object, an indirect object, or neither? …
neither
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2. methanol (ch₃oh) molecules experience hydrogen bonding. which of the…
b. only y
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stearic acid oleic acid complete the table. \tstearin\ttriolein is like…
| | stearin | triolein | | --- | --- | --- | | is likely liquid at room temperature | | $\boldsymbol{\checkmark}$ | | is a saturated fat | $\boldsymbol{\checkmark}$ | | | is likel…
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the model shows the chemical structure of a steroid. steroids have carb…
- Steroids have carbon atoms arranged in rings. - Steroids help regulate growth in the body.
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there are three sets of sketches below, showing the same pure molecular…
To solve this, we analyze the states of water at each temperature using its melting (0.0 °C) and boiling (100.0 °C) points: ### For Set A (246 °C): 246 °C is **above the boiling p…
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directions: please answer each fill in the blank with the best answer. …
positive ### Question 2
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11. ____ag₂o (s) ____ag + ____o₂ 12. ____s (s) + ____o₂ (g) → ____so₃ 1…
11. $2\text{Ag}_2\text{O}(s) ightarrow 4\text{Ag} + \text{O}_2$ 12. $\text{S}(s) + \text{O}_2(g) ightarrow \text{SO}_2$ 13. $\text{N}_2\text{O}_5(g) + \text{H}_2\text{O}(l) ightar…
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Question was provided via image upload.
5. $2\text{HgO} ightarrow 2\text{Hg} + \boldsymbol{1}\text{O}_2$ 6. $\boldsymbol{1}\text{Ca} + 2\text{H}_2\text{O} ightarrow \boldsymbol{1}\text{Ca(OH)}_2 + 2\text{H}_2$ 7. $2\tex…
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cleaning chemicals are generally not health hazards true false
False
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Question was provided via image upload.
1 $H_2$ + 1 $Cl_2$ → 2 $HCl$
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al₂(co₃)₃ 5. how many atoms of oxygen are in the compound above? 6. how…
9 ### Question 6
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in which orbitals would the valence electrons for selenium (se) be plac…
s orbital and p orbital
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which best explains why ionization energy tends to decrease from the to…
D. Electrons get farther from the nucleus. (Note: Assuming the options are labeled A - D as per typical multiple - choice, with the last option being the correct one. If the origi…
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which statement best describes how electrons fill orbitals in the perio…
A. Electrons fill orbitals in order of their increasing energy from left to right.
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the elements of which group are nonreactive? ○ halogens ○ alkaline eart…
C. noble gases
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which element is classified as an alkali metal? ○ rb ○ sr ○ zr ○ cl
A. Rb
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which substance is a mixture? ○ table salt ○ gasoline ○ aluminum ○ carb…
B. gasoline