how has the model of an atom changed overtime?
Answer:
This atomic model has changed over time. Scientists used the model to make predictions. Sometimes the results of their experiments were a surprise and they did not fit with the existing model. Scientists changed the model so that it could explain the new evidence.
Explanation:
What is 188.5°F in Celsius?
Answer:
That would be 86.944 Celsius
Explanation:
(188.5°F − 32) × 5/9 = 86.944°C
Answer: [tex]86.944444[/tex]°C
Explanation: (188.5°F − 32) × 5/9 = 86.944°C
Which pure substance can be classified as an element?
O
NO
Naci
H.SO
on edgnuity
the structure that houses dna
The nucleus (plural, nuclei) houses the cell's genetic material, or DNA, and is also the site of synthesis for ribosomes, the cellular machines that assemble proteins. Inside the nucleus, chromatin (DNA wrapped around proteins, described further below) is stored in a gel-like substance called nucleoplasm.
Change in oxidation number in zn is
Answer:
Equalize the changes in oxidation number Each Zn atom has lost two electrons, and each H atom has gained one electron. You need 2 atoms of H for every 1 atom of Zn. This gives us total changes of +2 and -2.
Explanation:
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And have an amazing day <3
What characterizes a homogeneous mixture?
A. The mixture settles out when left standing.
B. The substances are evenly distributed throughout.
O C. The mixture has different consistencies.
D. The substances are identifiable in the mixture.
Answer:
D. The substances are evenly distributed throughout.
How many mass would be contained in 0.01mol of NaOH
Answer:
∴ No. of atoms in 0.01 moles of NaOH = 6.02×10
23
×0.01=6.02×10
21
1.Which evidence did Wegener use to develop the theory of continental drift?
There is no evidence of glaciers anywhere in South America.
The climate of Siberia has always been the same.
Similar fossils were found on different continents.
The Rocky Mountains are taller than the Appalachian Mountains.
2.According to the theory of continental drift, which option indicates the order of how the continents changed positions?
B, C, A
C, B, A
A, B, C
C, A, B
3. The theory of continental drift proposes that the Earth's continents may have once been united as a supercontinent but have drifted apart over time.
What was the name of the supercontinent?
Americas
Gondwanaland
Laurasia
Pangaea
4.Part of Weneger's theory of continental drift was that the original supercontinent broke into two pieces.
What were these two land masses called?
Laurasia and Pangaea
Gondwanaland and Pangaea
Laurasia and Gondwanaland
Pangaea and Eurasia
5.
Over time Pangaea broke apart to form other continents.
Which group of modern-day continents composed Gondwanaland?
North America and South America
North America, Europe, and most of Asia
Africa, South America, Antarctica, Australia, and the subcontinent of India
Antarctica, South America, and Europe
Answer:
1. the second one
2. we need to know what the letters go to like is there a picture?
3. the first one
4.the last one
5.the third one
Explanation:
If the molecules in the above illustration react to form N2O4 according to the equation N2 + 2 O2 =N2O4 , the limiting reagent is , the number of N2O4 molecules formed is , and the number of molecules in excess is
Answer:
The limiting reagent is O2. The theoretical yield of N2O4 is 6 moles.
The limiting reactant is nitrogen.
In a chemical reaction, two or more species combine to form products. The amount of all the reactants in the system are usually not the same. The specie that is present in the least amount is called the limiting reactant. The reactant that is present in the greatest amount is called the reactant in excess.
Looking at the image, there are six oxygen molecules and two nitrogen molecules hence nitrogen is the limiting reactant and oxygen is the reactant in excess.
Since the equation of the reaction is; 2N2 + 4O2 --->2N2O4, it follows that there are two excess oxygen molecules that are left unreacted. Two N2O4 molecules are formed.
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Missing parts:
The illustration to the left represents a mixture of nitrogen (blue) and oxygen (red) molecules.
If the molecules in the above illustration react to form N2O4 according to the equation N2 + 2O2 N2O4
the limiting reagent is___?___
the number of N2O4 molecules formed is___?___
the number of___?___molecules in excess is___?___
The volume between the 50.00 mark and the valve of a buret is 5.58 . The buret reading of an upside down buret containing a pocket of hydrogen gas is 31.15 mL. What is the total volume of hydrogen in the buret?
We have that for the Question ,it can be said that The total volume of hydrogen gas is
Vt=24.43ml
From the question we are told
The volume between the 50.00 mark and the valve of a buret is 5.58 . The buret reading of an upside down buret containing a pocket of hydrogen gas is 31.15 mL. What is the total volume of hydrogen in the buret?
Generally
With the buret divided into three
The value section the middle and the top
With hydrogen gas contained in the middle and value area
We have
Volume of middle
Vm=(50-31.15)
Vm=18.85ml
For Valve area
Vv=5.58ml
Therefore
The total volume of hydrogen gas is
Vt=Vm+Vv
Vt=18.85+5.58
Vt=24.43ml
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If you had excess chlorine, how many moles of aluminum chloride could be produced from 12.0g of aluminum
Answer:
Hence, 0.455 mol of aluminum chloride could be produced from 12.0 grams of aluminum.
Explanation:
Given data:
•Mass of aluminum is 12.0 grams.
To find:
•Number of moles of aluminum chloride produced from Al.
The given reaction is as follows:
2A1+ 3Cl₂ → 2AlCl3
First, we have to find the number of moles of aluminum by the relation given below:
n = m M;
Where:
•n is the number of moles.
•m is the mass in grams.
•M is the molar mass in g/mol.
The molar mass of Al is 26.98 g/mol. Substitute the values in above equation to obtain the number of moles of aluminium as follows:
n = (12.0g)/(26.98g /mol)
= 0.445 mol
From the reaction stoichiometry, we can see that 2 moles of Al forms 2 moles of aluminium chloride (A1C13). This means, the number of moles of Al and AlCl3 is equal.
So, 0.445 mol Al will give 0.455 mol AlC13.
does food passes through liver, pancreas and appendix?
yes or no?
PLZ ANSWER ASAP PLZZZZZZZZZZZ
the following except____are examples of neutral oxides.
a. nitrogen (ii) oxide
b. carbon(ii) oxide
c. water
d. nitrogen (i) oxide.
Answer:
a nitrogen oxide
Explanation:
i think
A comparison of kinetic and potential energy is shown here with the position and motion of a round object with regards to a hill.
Which statements support the claim that an energy transfer is occurring as the ball rolls down the hill? Select ALL that apply.
A) the ball transfers energy to the air in the form of sound
B) the ball generates a gravitational field as it rolls downward
C)the potential energy is converted to kinetic energy as the ball rolls down the hill
D)the kinetic energy is converted to potential energy as the ball rolls down the hill
E) the ball loses kinetic energy but generates thermal energy as it moves down the hill
Answer:
YALL ITS A AND C
Explanation:
The potential energy is converted to kinetic energy as the ball rolls down the hill.
What are potential energy and kinetic energy?
The energy that is conserved or stored in a substance or object is known as potential energy. The position, organization, or state of the object or substance determines the amount of stored energy.
Potential energy mostly comes in two forms: The potential energy of gravity and Potential elastic energy.
The energy an object has as a result of motion is known as kinetic energy. A force must be applied to an object to accelerate it. We must put in effort to apply force.
Therefore, The potential energy is converted to kinetic energy as the ball rolls down the hill.
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Please help me: What mass of silver nitrate in water would need to be added to 5 g
of sodium chloride to ensure complete precipitation of the chloride?
Answer:
What are the 26 states of matter?
Bose–Einstein condensate.
Fermionic condensate.
Degenerate matter.
Quantum Hall.
Rydberg matter.
Rydberg polaron.
Strange matter.
Superfluid
Is Fluorine covalent, ionic or hydrate?
50 Points Help Me ASAP
change the following to the appropriate unit
1. 9.63 x 10–2 m ==> nm
2. 6.02 x 103 ks ==> s
3. 8.9 x 108 microgram ==> centigram
4. 4.12 x 10–4 Mg ==> g
5. 7.33 x 10 -2 TL ==> dL
6. 0.73 kL => L
7. 5.93 cm3 => m3
8. 498.82 cg => mg
[tex]\\ \sf\longmapsto 9.63\times 10^{-2}m=9.63\times 10^{-2}\times 10^{-9}m=0.0963\times 10^{-9}m=0.0963nm[/tex]
[tex]\\ \sf\longmapsto 6.02\times 10^3ks=6.03\times 10^6s[/tex]
[tex]\\ \sf\longmapsto 8.9\times 10^8\mu g=8.9\times 10^4cg[/tex]
[tex]\\ \sf\longmapsto 4.12\times 10^{-4}Mg=4.12\times 10^{-1}g=0.412g[/tex]
[tex]\\ \sf\longmapsto 7.33\times 10^{-2}Tl=7.33\times 10dL=73.3dL[/tex]
[tex]\\ \sf\longmapsto 0.73kL=0.73(1000)L=730L[/tex]
[tex]\\ \sf\longmapsto 5.93cm^3=0.00000593m^3[/tex]
Done!
How could the AX3 molecular structure (one central atom with three bonded atoms) be non-polar even with bond dipoles present?
options:
1. If there were no lone pairs on the central atom
2. If there were one lone pair on the central atom
3. If there were two lone pairs on the central atom
4. If there were three lone pairs on the central atom
The AX3 molecular structure (one central atom with three bonded atoms) can be non-polar even with bond dipoles present If there were no lone pairs on the central atom. Option 1 is correct.
The molecular structure or shape is a 3-D pattern showing the arrangement of atoms of a molecule.
The molecular structure of AX3 is said to be composed of a central atom connected and bounded to three atoms which are equally spaced at an angle of 120° towards one another. It has a shape of trigonal planar and its sp² hybridized that does not have any lone pair.
The polarity of a molecule or a compound has to do with the presence of lone pair in the central atom. Since AX3 has no lone pair of electrons in its central atom it is said to be non-polar.
Example of compounds that exhibit AX3 with no lone pair is: BF₃ and CO₃²⁻
Therefore, we can conclude that we've understood what is molecular structure and how to identify the molecular structures that are polar and non-polar in nature.
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Layla is helping to clean car parts with a single chemical, but it isn't working. She washes her hands and tries a different chemical, which also does not work. She resumes with the first chemical without washing her hands. This time, the cleaning process works, but she begins to get dizzy and nauseated. What can Layla infer about the possible reason for her illness?
It is an acute effect of two toxins with a synergistic relationship.
It is a chronic effect of the second toxin she used to clean the parts.
The first chemical has an antagonistic relationship with the second.
The second chemical causes acute affects, and the first causes chronic affects.
Layla is helping to clean car parts with a single chemical, but it is not working. She washes her hands and tries a different chemical, which also does not work. She resumes with the first chemical without washing her hands. This time, the cleaning process works, but she begins to get dizzy and nauseated.
The first chemical is possibly toxic and may have caused Layla to become dizzy and nauseated when she resumed cleaning car parts without washing her hands after trying the second chemical. Layla could have accidentally ingested or absorbed some of the first chemical when she touched her mouth or rubbed her eyes while still contaminated with the chemical.A chronic effect is an effect that occurs as a result of exposure to a substance or substances over an extended period. The effect may not become evident until long after the exposure has occurred and may persist even after the exposure has ended. On the other hand, an acute effect is an effect that occurs soon after exposure to a substance or substances and usually lasts for a short period.The symptoms Layla experienced after resuming cleaning car parts with the first chemical are consistent with acute toxicity, which may cause symptoms such as dizziness, nausea, headache, skin irritation, and even death. Therefore, it is possible that the first chemical causes acute effects rather than chronic effects. However, the second chemical, which Layla washed her hands with, may also have toxic effects, but not necessarily acute ones.In conclusion, the fact that Layla experienced symptoms of dizziness and nausea after resuming cleaning car parts with the first chemical without washing her hands indicates that the chemical could be toxic and may have caused acute effects.For such more question on nauseated
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If a steam reforming line processes methane at a temperature of
725.0°C and a pressure of 12.00 atm, what is the volume (in L) that
20.0 moles of methane would occupy in the reactor?
Answer:
ideal gas law. PV=nRT
Explanation:
pressure x volume = #moles x R (constant of 8.31) x temp
Find the sum of coefficients for all reactants and products.
CuBr2 + H3PO4 ⇨ Cu3(PO4)2 + HBr
The sum of coefficients for all reactants and products of given reaction is 12.
[tex]CuBr_{2} + H_{3}PO_{4}[/tex]⇨ [tex]Cu_{3} (PO_{4})_{2} + HBr[/tex]
For finding coefficients each molecules in reactant and product, first we have to balanced the given chemical equation.
What is balanced chemical equation?The chemical equation in which number of atoms for each elements and total charges is same in both side, reactant as well as product in a reaction.
Example: Let the unbalanced chemical equation is,
[tex]CuBr_{2} + H_{3}PO_{4}[/tex]⇨ [tex]Cu_{3} (PO_{4})_{2} + HBr[/tex]
So, the balanced chemical equation become.
[tex]3CuBr_{2} + 2H_{3}PO_{4}[/tex] ⇨ [tex]Cu_{3} (PO_{4})_{2} +6 HBr[/tex]
Reactant Product
The number placed prior to the each molecules is called coefficient of reactant and product.
So, the total coefficient for reactant and product are 3 + 2 + 1 + 6 = 12.
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A spider catches and eats a caterpillar that depends on plant leaves for food.
Draw a food chain that tracks how the sun's energy gets to the spider.
Answer: The caterpillar stage of the invasive winter moth ( Operophtera brumato) eats young, tender leaves, sometimes before the leaves even get a chance to emerge from the bud. Energy from the Sun is transformed into chemical energy. 1. , which is passed along in a food chain
Explanation: Can't draw on here, hope this help u tho
Which of the following must be true in order for a reaction to have no excess reactants?
A) It must be a double-replacement reaction.
B) Reactants must be present in equal amounts.
C) Reactants must be present in the exact molar ratios in the balanced chemical equation.
D) It must occur at a high temperature.
Answer:
C) Reactants must be present in the exact molar ratios in the balanced chemical equations.
Explanation:
What is a physical change and a chemical change
Answer:
A physical change --> is the change in appearance or form Example --> ice melting.
A chemical change --> is the change in chemical composition. Example --> rust
Additionally, physical changes can be reversible (water melting or freezing), while chemical changes can't. Rust cannot be reversed.
Buffer #1: 0.15 M HF(aq) and 0.10 M NaF(aq)
Buffer #2: 0.090 M HF(aq) and 0.060 M NaF(aq)
Fill in the following sentence:
The pH values of Buffers #1 and #2 are _______, and the buffering capacity of Buffer #1 is _______ than that of Buffer #2.
a) unequal; higher
b) equal; lower
c) unequal; lower
d) equal; higher
Buffer #1: 0.15 M HF(aq) and 0.10 M NaF(aq) Buffer #2: 0.090 M HF(aq) and 0.060 M NaF(aq). The pH values of Buffers #1 and #2 are equal, and the buffering capacity of Buffer #1 is higher than that of Buffer #2.
A buffer is a solution that is capable of withstanding changes in pH caused by the introduction of acid or base substances. It may neutralize tiny quantities of additional acid or base, allowing the pH of the solution to remain reasonably constant.
For buffer 1;
[HF] = 0.15 M [NaF] = 0.10 MUnder Standard Conditions, Ka(acid dissociation constant) for HF = 3.5 × 10⁻⁴
pKa = -log Ka
pKa = -log (3.5 × 10⁻⁴)
pKa = 3.454
The formula for calculating the buffer value can be represented by:
[tex]\mathbf{pH = pKa + log \dfrac{([A^+])}{([HA])}}[/tex]
[tex]\mathbf{pH = 3.454 + log \Big(\dfrac{0.10}{0.15}}\Big)[/tex]
pH = 3.2779
For Buffer 2;
[HF] = 0.090 M [NaF] = 0.060 M[tex]\mathbf{pH = 3.454 + log \Big(\dfrac{0.06}{0.09}}\Big)[/tex]
pH = 3.2779
We can see that the pH of buffer 1 is equivalent to the pH of buffer 2.
Buffer capacity measures a solution's capacity to endure pH fluctuations by either accepting or detaching H+ and OH- ions.
For Buffer 1:
The buffer capacity can be expressed by using the formula:
[tex]\mathbf{\beta = \dfrac{2.3 \ Ka [H^+] [C]}{(Ka+ [HA])^2}}[/tex]
where;
C = total concentration of buffer components i.e. [HA] + [A⁻][tex]\mathbf{\beta = \dfrac{2.3 \ \times 3.5 \times 10^{-4} \times (0.15) (0.15 \times 2)}{(3.5 \times 10^{-4} + (0.15)^2 }}[/tex]
[tex]\mathbf{\beta = \dfrac{3.6225 \times 10^{-5}}{0.02260}}[/tex]
[tex]\mathbf{\beta = 0.0016}[/tex]
For Buffer 2:
[tex]\mathbf{\beta = \dfrac{2.3 \ \times 3.5 \times 10^{-4} \times (0.09) (0.09 \times 2)}{(3.5 \times 10^{-4} + (0.09)^2 }}[/tex]
[tex]\mathbf{\beta = \dfrac{1.3041 \times 10^{-5}}{0.008163}}[/tex]
[tex]\mathbf{\beta = 0.00159}[/tex]
Therefore, we can conclude that the pH values of Buffers #1 and #2 are equal, and the buffering capacity of Buffer #1 is higher than that of Buffer #2.
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Explain the difference between accuracy and precision.
Answer:
The difference between accuracy and precision is both precision and accuracy are two ways of how scientists think about error. However, accuracy refers to or meaning to how close a measurement is to the true or accepted value. On the other hand, precision refers to or meaning to how close measurements of the same item are to each othe .... But scientists use the best quality of scientific observations and are both accurate and precise.
A d6 electron configuration will typically have an overall spin of
Answer: 2
Explanation:
How does a Camel prevent the loss of water from their body?
Camels lose less water through their urine and feces than many other mammals. Their kidneys concentrate water heavily, leading to salty urine. The intestines also reabsorb water from intestinal material as it is digested, so dry feces are produced.
The atomic mass of an element can change as the number of________ changes.
(Options:)
a. neutrons
b. electrons
c. protons
Answer: a: neutrons but it might be b
Explanation:
i learn this in 7 grade and it was a long time so i might be wrong
Daje 25pkt bo tylko tyle mam :(( pomoże ktoś?
Answer:
brak syna 25 punto, syn 13
Explanation: