Chimie
Réactions chimiques, stœchiométrie, structures moléculaires et propriétés.
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question 1 0.25 pts how many neutron are in an atom of calcium-40? ques…
20 ### Question 2
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11. it rains and puddles form on the ground. the sun comes out and the …
When it rains, water forms puddles (liquid water). When the sun shines, the water in the puddle absorbs heat, increasing the kinetic energy of water molecules. The liquid water mo…
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choose all that are correct. an electron... □ ...has a mass of 1 gram. …
-...a negligible mass. -...is located in the empty space surrounding the nucleus. -...has a charge of 1-.
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10. explain why sugar dissolves faster in hot tea than cold tea. (think…
Sugar dissolves faster in hot tea than cold tea because temperature influences molecular motion. Hot tea has higher - temperature water, so water molecules move faster (have highe…
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to see how well you did. adjectival phrase modifying a noun adjectival …
To solve this, we analyze each sentence and match the underlined phrase to its function: ### 1. Carlos was pleased \underline{with his chemistry grade}. - The phrase "with his che…
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the universal gas law, ( pv = nrt ), describes the relationship among t…
\( 8.31 \)
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why is it important to understand chemical kinetics? to maximize the am…
The correct option is: to control and optimize chemical reactions
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question 6 how do we relate the reaction rate to the rate of disappeara…
The correct option is the one stating "we use the stoichiometric coefficients" (the fourth option in the list of choices provided for the question).
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question 5 how is the instantaneous reaction rate determined? by measur…
By calculating the slope of a tangent at a specific time.
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question 4 what is the instantaneous reaction rate? the initial reactio…
the reaction rate at a given time point
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question 3 as a chemical reaction happens, how does the reaction rate c…
It gets slower.
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question 2 the change in concentration of reactants over time is always…
A. always negative
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question 1 what are the units of reaction rate? options: l/min, atm/s, …
B. M/s
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6 multiple choice 10 points sanai was monitoring the oil spill in the g…
C. Hydrophobic interactions
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nombre: destiny ramos práctica de estructura atómica completa los espac…
To solve the atomic structure table, we use the following relationships: - Atomic Number (Z) = Number of Protons = Number of Electrons (in neutral atoms). - Mass Number (A) = Numb…
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name jayden colemun period 2 date 4/11/25 isotopes, ions, and atoms wor…
Let's solve each row step by step using the given formulas: \( \text{Atomic \#} = \# \text{ of protons} \), \( \text{Mass \#} = \text{Atomic \#} + \text{neutrons} \), and \( \text…
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name jayden coleman period 2 date isotopes, ions, and atoms worksheet a…
Mass #: 36; # \( p^+ \): 17; # \( e^- \): 17; Symbol: \( ^{36}_{17}\text{Cl} \) ### Problem 2:
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5. define ozone and explain its purpose.
Ozone is a triatomic molecule ($O_3$) of oxygen. Stratospheric ozone forms a layer that absorbs harmful UV radiation, protecting life; ground - level ozone (pollutant) is a by - p…
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name ________________________ period __________ isotopes, ions, and ato…
To solve the problems in the "Isotopes, Ions, and Atoms Worksheet 2", we use the following relationships: - Atomic number (\(Z\)) = number of protons (\(p^+\)) - Mass number (\(A\…
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which of the following best explains why a structural formula of a chem…
A. Both formulas identify the specific atoms in a particular compound. However, a structural formula also shows how the atoms in a compound are bonded together.
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roberto examines two molecular models. he sees that the atoms are the s…
B. two geometric isomers that have the same molecular formula
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what is a disadvantage of using a structural model to show a chemical c…
A. Structural models provide minimal three - dimensional information.
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which of the following best describes a possible carbon compound? one c…
One carbon atom forms a double bond with an oxygen atom and two single bonds with two hydrogen atoms
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which best explains the difference between a ball-and-stick model of a …
The option: "Ball - and - stick models show the bonds between atoms, but not the relative sizes of atoms. Space - filling models show the relative sizes of atoms, but not the bond…
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phenomena in pharmaceutics. 5 points 2. draw and completely label a hyp…
A hypothetical phase diagram for menthol - camphor mixture is drawn with: - **Axes**: \(x\) - axis (mass fraction of camphor, \(0\) to \(1\)), \(y\) - axis (temperature, °C). - **…
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which of the following is an organic compound? ○ ammonia (nh₃) ○ calciu…
C. octane ($C_8H_{18}$)
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gina wants to use models to better understand how the types of bonds in…
the ball - and - stick model
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structural isomers are chemical compounds that have the same atoms that…
the same atoms that are arranged in different orders.
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which molecular formula corresponds to this model of a chemical compoun…
\(C_2H_2O_4\) (the option corresponding to \(C_2H_2O_4\))
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how many isomers does hexane (c₆h₁₄) have? ○ four ○ five ○ six ○ seven
B. five
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9. why do all isotopes of an element have the same chemical properties?…
All isotopes of an element have the same number of protons (same atomic number), so they have the same electron configuration (especially the number of valence electrons). Since c…
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examine the nuclear reaction: (ce{_1^1h + _0^1n -> _1^2h}). why is this…
C. A change has occurred in a nucleus.
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which radioisotope is used as a tracer in nuclear scanning? ○ carbon -1…
C. technetium - 99m
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an article about half-lives describes a daughter isotope. what is a dau…
A. the isotope that forms from the radioactive decay of a less stable isotope
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consider the reaction below. 2k + br₂ → 2k⁺ + 2br⁻ what is being reduce…
only \( \text{Br}_2 \) (the option with "only \( \text{Br}_2 \)")
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7. atoms of the same element that differ in the number of neutrons they…
isotopes
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consider the half reactions below for a chemical reaction. zn \\longrig…
A. \(Zn(s)+Cu^{2+}(aq) ightarrow Zn^{2+}(aq)+Cu(s)\)
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the hydrogen bonds in water will not directly influence which of the fo…
A. adhesion of the setae to a walking surface
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what is a characteristic of all fuel cells? energy from the sun is conv…
B. Electrical energy is produced from oxidation reactions.
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5. what is a... the same number of protons 6. what does an element’s at…
An element’s atomic number represents the number of protons in the nucleus of an atom of that element.
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which answer best describes what is happening in the following redox re…
Iron is oxidized to form rust.
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uranium-232 has a half-life of 68.8 years. after 344.0 years, how much …
3.13 g
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the hydrogen bonds in water will not directly influence which of the fo…
A. adhesion of the setae to a walking surface
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consider the half reaction below. 2cl⁻(aq) → cl₂(g) + 2e⁻ which stateme…
A. Chlorine is losing electrons and being oxidized
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the reaction below was carried out in an acidic solution. \text{i}^- + …
A. Although it is unbalanced, it can be balanced by using the half - reaction method
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elements and isotopes (pag 5. what is a chemical element?
A chemical element is a pure substance made up of atoms with the same number of protons (same atomic number) in their nuclei, and it cannot be broken down into simpler substances …
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what is the oxidation number for n in the compound nh₃? (recall that h …
The oxidation number of N in \( NH_3 \) is -3, so the correct option is the one with -3 (the first option: -3).
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what part of an atom is involved in a chemical reaction? ○ proton ○ neu…
D. electron (assuming the options are labeled A - D as proton, neutron, nucleus, electron respectively)
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which electrolyte is used in an alkali fuel cell? ○ a high temperature …
an aqueous potassium hydroxide solution
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4. why are atoms neutral despite having charged particles?
Atoms are neutral because the number of positively - charged protons in the nucleus is equal to the number of negatively - charged electrons outside the nucleus. The positive and …
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which element does x represent? options: \\(_{36}^{95}\\text{kr}\\), \\…
\(_{36}^{97}\text{Kr}\) (the option with atomic number 36 and mass number 97, i.e., the third option in the list: \(\boldsymbol{_{36}^{97}\text{Kr}}\))
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what is most of the sun’s energy a result of? nuclear fusion nuclear fi…
A. nuclear fusion
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reminders: 1. in a neutral atom the number of protons equals the number…
s to Short Questions: 1. **What is an ion?** An ion is an atom (or group of atoms) that has gained or lost electrons, resulting in a net positive or negative charge. 2. **What doe…
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over time, gravity gradually pulls the debris together and forms the mo…
The chemical composition of rocks in the Moon's crust is expected to be similar to that of Earth's crust.
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a sample originally contained 1.28 g of a radioisotope. it now contains…
3
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a meteorite contains 0.17 g of nickel-59, a radioisotope that decays to…
5 (corresponding to the option "5")
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an article about half-lives describes a parent isotope. what is a paren…
D. an isotope that undergoes radioactive decay to form a more stable isotope
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samarium-146 has a half-life of 103.5 million years. after 1.035 billio…
0.200 g
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which statement is true about radiocarbon dating? after it dies, an org…
The half - life of C - 14 is 5,730 years.
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sodium-24 has a half-life of 15 hours. after 45 hours, how much sodium-…
6.25 g (Option: 6.25 g)
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lendium-176 has a half-life of 3.85 × 10¹⁰ years. after 1.155 × 10¹¹ ye…
2.10 g (corresponding to the option "2.10 g")
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lutetium-176 has a half-life of 3.85 × 10¹⁰ years. after 1.155 × 10¹¹ y…
First, find the number of half - lives \(n\) passed. The formula for the number of half - lives is \(n=\frac{t}{T_{1/2}}\), where \(t = 1.155\times10^{11}\) years and \(T_{1/2}=3.…
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1. what is an isotope? 2. what does the number next to isotopes signify…
Isotopes are atoms of the same element with the same number of protons (same atomic number) but different numbers of neutrons (different mass numbers). ### 2. What does the number…
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emission spectra of elements in the bohr model of an atom, negatively c…
Elements have unique emission spectra because each element has a distinct electron energy - level structure, leading to unique energy differences between levels and thus unique wa…
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which drug contains the chemical thc and affects specific receptors in …
C. marijuana
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16. a chemist is observing a solution’s temperature over a four-hour pe…
La temperatura después de cuatro horas es $-14.8^\circ\text{C}$. ### Problem 18
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concept check 1. predict what would happen if you mixed potassium chlor…
Potassium chloride (KCl) will dissolve in water. The ionic bonds in KCl break, and \( \text{K}^+ \) and \( \text{Cl}^- \) ions become hydrated (surrounded by water molecules), res…
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density inquiry lab reflection questions: 1. describe the process you u…
To calculate density, use the formula \( ho = \frac{m}{V} \) (density = mass/volume). For an unknown liquid, measure the mass of the liquid (using a balance: mass of cylinder + li…
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11. how much time does it take oxygen (o) to change into silicon (si)? …
Oxygen atoms cannot change into silicon atoms through ordinary chemical or typical physical processes. Changing an element (altering the number of protons in the nucleus) is not a…
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evidence: | | mass of liquid (g) | volume (ml) | density (g/ml⁻¹) | sub…
To solve for the mass, density, and identify the substance, we need additional information (e.g., known density values of common substances or the mass of the liquid). Since the p…
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descriptive language that appeals to the senses and creates vivid menta…
Imagery ### 2.
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the four pieces of metal, and uses the water displacement method to mea…
To solve for the volume of the metal, we use the water displacement method, where the volume of the metal is the difference between the volume of water + metal and the volume of w…
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evidence: | | mass of liquid (g) | volume (ml) | density (g/ml³) | subs…
### Brief Explanations: 1. Density is a **property** of matter (it describes a characteristic of matter). 2. Density is calculated using the formula \( \text{Density} = \frac{\tex…
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1pt wavelength is a measure of the horizontal distance between _______.…
A. two wave crests
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chemistry data and graphing a student finds four pieces of a lustrous m…
| Metal # | Mass of Metal | Volume of Water | Volume of Water + Metal | Volume of Metal | |---------|---------------|-----------------|-------------------------|-----------------|…
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this passage describes a chemical reaction. read the passage. then, fol…
To solve this, we analyze the passage: - **Reactants** are substances that react (mixed when the barrier breaks). The passage says the glow stick has hydrogen peroxide ($\ce{H_2O_…
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1pt how do water molecules move as part of deep ocean waves? a. in circ…
A. in circles
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this passage describes a chemical reaction. read the passage. then, fol…
| Substance | Reactant | Product | |--|--|--| | lactic acid ($\ce{C_3H_6O_3}$) | | $\boldsymbol{\checkmark}$ | | lactose ($\ce{C_{12}H_{22}O_{11}}$) | $\boldsymbol{\checkmark}$ | …
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this passage describes a chemical reaction. read the passage. then, fol…
To solve this, we analyze the passage: Reactants are substances that combine (salicylic acid, acetic anhydride), products are formed (aspirin, acetic acid). | Substance | Reactant…
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13. which letter does not represent a current sublevel of an energy lev…
c. 9 ### Question 15: How many electrons are held in \( n = 3 \)?
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procedure (continued): 16. refer back to your data table on slide 4, an…
To solve for the identity of each mystery liquid, we compare their densities (which would be obtained from the data table on Slide 4, though not fully shown here, we can assume ty…
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when tap water contains high levels of calcium, a substance called calc…
| Substance | Reactant | Product | | --- | --- | --- | | calcium carbonate ($\ce{CaCO3}$) | $\boldsymbol{\checkmark}$ | | | calcium citrate ($\ce{Ca3C12H10O14}$) | | $\boldsymbol{…
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this passage describes a chemical reaction. read the passage. then, fol…
| Substance | Reactant | Product | |------------------------|----------|---------| | ammonia (NH₃) | ✔️ | ❌ | | hydrazine (N₂H₄) | ❌ | ✔️ | | sodium chloride (NaCl) | ❌ | ✔️ | | s…
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check for understanding: describe the process you used to find the dens…
To find the density of each liquid, I $\boldsymbol{divided}$ the $\boldsymbol{mass}$ by the $\boldsymbol{volume}$ of each unknown substance.
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identify the parts of an atom diagram of an atom with labeled arrows | …
To calculate the average atomic mass, we use the formula: \[ \text{Average Atomic Mass} = \sum (\text{Isotope Mass} \times \text{Percent Abundance (in decimal)}) \] ### Hydrogen #…
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reference the conversion below to determine how many liters are in 10.0…
9.46 L
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mass number → a (n of protons + n of neutrons) x element atomic number …
Isotope: Same number of $\boldsymbol{\text{protons}}$ and $\boldsymbol{\text{electrons}}$ (in neutral), different number of $\boldsymbol{\text{neutrons}}$. Ions: Same number of $\…
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dress the part in the laboratory a scientist works in a ________. labor…
1. A scientist works in a **laboratory**. Laboratories are where scientists run **experiments** instead of their **opinions** and make most of their observations, measurements and…
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age of science 1747 andraeas marggraf discovers that beet sugar is iden…
B. It documents key events in the sugar and sweetener industries.
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what happens if you heat a diamond to 1,405°f?
it
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6 organize the steps in this experiment according to the scientific met…
To solve this, we follow the scientific method steps: observation, question, hypothesis, experiment, data collection, conclusion. ### Step 1: Observation The first step in the sci…
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6 organize the steps in this experiment according to the scientific met…
To solve this, we follow the scientific method steps: observation, question, hypothesis, experiment, data collection, conclusion. ### Step 1: Observation The first step in the sci…
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choose all that are correct. a neutron... ...has a mass of 1 gram. ...h…
-...has a mass of 1 amu. -...is located in the nucleus. -...has no charge.
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6. a piece of metal has a volume of 30.0 cm³ and a mass of 252 g. what …
The density is $8.4\ \text{g/cm}^3$, and the metal is likely brass (or a similar metal with a density around this value).
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property physical or chemical? melting point of 1,538°c rusts in the pr…
s (from top to bottom): 1. Physical 2. Chemical 3. Physical 4. Physical
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which statement best supports your claim? choose 1 answer: a the sulfur…
B. New bonds form between rubber molecules and sulfur. This creates a substance with different properties.
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using the information in the table above, make a clai vulcanizing rubbe…
chemical
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which of the following indicate that a chemical change likely occurred?…
C. bubble formation from a new gas, D. light and heat production
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which statement best describes what happens during a chemical change? c…
B. The identity of the original substance changes.
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complete the statement. a chemical property is a characteristic of a su…
C. describes how a substance behaves in a chemical change