Answer:
D
Explanation:
The nuclear model of the atom was proposed by Ernest Rutherford.
In his submission, the atom consists of a dense positive nucleus with electrons moving round this nucleus as planets move round the sun. He likened his model to the solar system. The nucleus is at the center of this system just as the sun is at the center of the solar system.
Answer:
D.The nuclear model describes the atom as a dense, positive nucleus surrounded by a cloud of negative electrons.
Explanation:
A Cu/Cu2 concentration cell has a voltage of 0.22 V at 25 o C. The concentration of Cu2 in one of the half-cells is 1.5 x 10-3 M. What is the concentration of Cu2 in the other half-cell
Answer:
The concentration is [tex] [Cu^{2+}]_a = 10^{-10.269} [/tex]
Explanation:
From the question we are told that
The voltage of the cell is [tex]E = 0.22 \ V[/tex]
Generally the reaction at the cathode is
[tex]Cu^{2+} _{(aq)} + 2e^{-} \to Cu_{s}[/tex] the half cell voltage is V_c = 0.337 V
Generally the reaction at the anode is
[tex]Cu _{(s)} \to Cu^{2+} _{(aq)} + 2e^{-}[/tex] the half cell voltage is V_a = -0.337 V
Gnerally the reaction of the cell is
[tex]Cu_{(s)} + Cu^{2+} _{(aq)} \to Cu^{2+}_{(aq)} + Cu_{(s)}[/tex]
At initial the voltage is V = 0 V
Generally the voltage of the cell at 25°C is
[tex]E = V - \frac{0.0591}{n} log \frac{[Cu^{2+}] _a}{[Cu^{2+}]_c}[/tex]
Here n is number of of electron and it is 2
So from the question we are told that one cell has a concentration 1.5 x 10-3 M
Let assume it is [tex][Cu^{2+}]_c[/tex]
So
[tex]0.22= 0 - \frac{0.0591}{2} log \frac{[Cu^{2+}] _a}{ 1.5 * 10^{-3} }[/tex]
=> [tex]-7.445 = log \frac{[Cu^{2+}] _a}{ 1.5 * 10^{-3} }[/tex]
=> [tex]-7.445 = log [Cu^{2+}_a] - log [1.5*10^{-3}][/tex]
=> [tex]-7.445 + log [1.5*10^{-3} = log [Cu^{2+}_a] [/tex]
=> [tex]-7.445 - 2.824 = log [Cu^{2+}_a] [/tex]
Taking the antilog
=> [tex] [Cu^{2+}]_a = 10^{-10.269} [/tex]
=> [tex] [Cu^{2+}]_a = 5.38 *10^{-11} \ M [/tex]
For many years, experiments showed that light had wave-like properties. For this reason, scientists described light
as a wave. More recently, experiments produced data that could not be explained by the wave theory of light. The
idea of particle properties was introduced
Why did the theory of light change over time?
O The theory was too old and needed to be updated
New scientists did not agree with the older theory
O The scientific question changed, so the theory had to change.
O Repeated experimentation introduced new discoveries.
Answer:
Repeated experimentation introduced new discoveries.
Explanation:
Science is not a static body of knowledge, scientific theories change as new evidence emerges from repeated experiments.
For many years, the wave theory of light was generally held by almost all scientists.
Further experiments such as photoelectric effect and Compton effect lent credence to the the particle theory of light, hence the answer
Answer:
D
Explanation:
Repeated experimentation introduced new discoveries.
Measurements show that unknown compound X has the following composition: element mass % carbon 41.0% hydrogen 4.58% oxygen 54.6% Write the empirical chemical formula of X.
Answer:
CHO
Explanation:
Carbon = 41%, Hydrogen = 4.58%, oxygen = 54.6%
Step 1:
Divide through by their respective relative atomic masses
41/ 12, 4.58/1, 54.6/16
3.41 4.58 3.41
Step 2:
Divide by the lowest ratio:
3.41/3.41, 4.58/3.41, 3.41/3.41
1, 1, 1
Hence the empirical formula is CHO
Answer:
The empirical formula of X is C3H4O3.
Explanation:
Observing a phenomenon in the lab includes which of the following?
Throwing away irrelevant items
Sorting through and disposing of police reports
Collecting evidence
Identifying unique features of evidence
Answer:
D
Explanation:
Identifying unique features of evidence
A laboratory is a place where scientific investigations and experiments are conducted. Observing a phenomenon in the lab includes identifying unique features of evidence. Thus, option D is correct.
What is observation?
An observation is said to be the deduction that is seen or heard and is due to the actions of the process or event that are gained from the information from a conducted experiment.
It is an important factor in an experiment and research and is used in the lab to falsify or prove the hypothesis. It is made based on the experimental setup and involves various steps.
The observations are used to draw conclusions and inferences based on the detailed identification of the characteristics of the evidence. The evidence supports the observation.
Therefore, option D. the features of evidence are the correct option.
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Someone plz hello me ASAP it would be appreciated on question 2 and 3 btw
Answer:
2 should be potential energy and 3 should be A
Explanation:
What happens when the elements in group 2 react with iodine
Answer:
Yah
Explanation:
Which of the following reactions would you expect to produce the most energy?
A. Nuclear fusion of two hydrogen isotopes.
B. Combustion of hydrogen gas.
C. Combination of a strong acid and a strong base.
D. Burning a large hydrocarbon, such as oil.
Answer:
A
Explanation:
Nuclear fusion is a much more powerful reaction than any of the others.
Nuclear fusion of two hydrogen isotopes would expect to produce the most energy. Therefore, option (A) is correct.
What is nuclear fusion?Nuclear fusion can be defined as when two or more nuclei fuse together to form a single heavier nucleus. In this reaction, the matter is generally not conserved due to some of the mass of the nuclei being converted to energy.
For nuclear fusion, the nuclei must be brought closer to the reaction occurring. Each star in the universe, including sun, is shining due to nuclear fusion reactions. They produce large amounts of energy in this process.
In the Sun's core, hydrogen nuclei are get transformed into helium nuclei which are known as nuclear fusion. It takes place when four hydrogen nuclei fuse into each helium nucleus. During the Nuclear fusion process, some of the mass of hydrogen nuclei is transformed into energy.
Therefore, nuclear fusion is where hydrogen atoms combined to form helium to produce the most energy.
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Which group beleow is correctly placed in order of least to most electronegative
K, Si, O, F
Si, K, O, F
F, O, SI, K
F, K, O, Si,
Which is one way that minerals crystallize from materials dissolved in water?
from the air
from solutions that evaporate
from hot water solutions when water boils
from the soil
Answer:
the second answer its science behind it
Answer:
b
Explanation:
A tank at is filled with of dinitrogen difluoride gas and of chlorine pentafluoride gas. You can assume both gases behave as ideal gases under these conditions. Calculate the mole fraction and partial pressure of each gas, and the total pressure in the tank. Be sure your answers have the correct number of significant digits.
The question is incomplete, the complete question is;
A 8.00 L tank at 2.64 °C is filled with 9.82 g of chlorine pentafluoride gas and 10.1 g of dinitrogen difluoride gas. You can assume both gases behave as ideal gases under these conditions. Calculate the mole fraction and partial pressure of each gas, and the total pressure in the tank. Be sure your answers have the correct number of significant digits.
Answer:
See explanation for details
Explanation:
Number of moles of N2F2 = mass/ molar mass
Molar mass of N2F2 = 66 g/mol
Number of moles = 10.1 g/66 = 0.15 moles
Number of moles of ClF5 = 9.82 g/130 g/mol= 0.08 moles
Molar mass of ClF5= 130g/mol
Total number of moles = 0.15 moles + 0.08 moles = 0.23 moles
Given that;
T= 2.64 °C + 273 = 275.64 K
n= 0.23 moles
R= 0.082 Latmmol-1K-1
V= 8.00 L
P= ??
From;
PV =nRT
P= nRT/V
P= 0.23 ×0.082 × 275.64/8.00
P= 0.65 atm
Mole fraction of N2F2= 0.15/0.23 = 0.65
Partial pressure = mole fraction × total pressure = 0.65 × 0.65 = 0.42 atm
Mole fraction of ClF5 = 0.08/0.23 = 0.35
Partial pressure of ClF5 = mole fraction × total pressure = 0.35 × 0.65 = 0.22 atm
A 5-kg quantity of radioactive isotope decays to 2 kg after 10 years. Find the decay constant of the isotope.k = _____
Answer:
k = -0.09165 years^(-1)
Explanation:
The exponential decay model of a radioactive isotope is generally given as;
A(t) = A_o(e^(kt))
Where;
A_o is quantity of isotope before decay, k is decay constant and A(t) is quantity after t years
We are given;
A_o = 5 kg
A(10) = 2kg
t = 10 years
Thus;
A(10) = 2 = 5(e^(10k))
Thus;
2 = 5(e^(10k))
2/5 = (e^(10k))
0.4 = (e^(10k))
In 0.4 = 10k
-0.9164 = 10k
k = -0.9164/10
k = -0.09165 years^(-1)
g A 0.4395 g sample of aluminum reacts according to our experiment to produce alum. 5.1629 g of dried alum crystals are recovered. What is the percent yield of the experiment?
Answer:
92.75%
Explanation:
The overall chemical equation for the reaction in the preparation of alum from the aluminium can be expressed as:
[tex]\mathtt{2Al + 2KOH + 4H_2SO_4 +2H_2O \to 2KAl(SO_4)_2 2H_2O +3H_2}[/tex]
From above; we will see that 2 moles of Aluminium react with sulphuric acid and water to produce 2 moles o aluminium alum.
Therefore, the theoretical yield can be determined as:
[tex]=0.4395 \ g Al \times \dfrac{1 \ mol \ Al}{27 \ g Al }\times \dfrac{2 \ mol \ KAl(SO_4)_2}{2 \ mol \ Al}\times \dfrac{294.23 \ KAl(SO_4)_2}{1 \ mol \ KAl(SO_4)_2}[/tex]
= 4.789g of [tex]KAl(SO_4)_2[/tex]
To find the percent yield, we need to divide the actual yield by the theoretical yield and then multiply it with 100.
∴
percent yield = ( mass of alum(g)/theoretical yield(g) ) × 100
percent yield = ( 4.789g / 5.1629g ) × 100%
percent yield = 0.9275 × 100%
percent yield = 92.75%
Thus, the percent yield of the experiment 92.75%
Rupert had three substances. A brown substance was a liquid at room
temperature. He hit each of the other two with a hammer. A blue crystal
cracked but did not break. A silver substance flattened but did not crack.
Which two statements could be true?
A. The brown substance is ionic
B. The silver substance is ionic
C. The brown substance is molecular
D. The blue substance is ionic
Answer:
its C and D
C. The brown substance is molecular
D. The blue substance is ionic
Explanation:
did the test !
Two correct statements are B) The silver substance is ionic
C) The brown substance is molecular.
What kind of substance is silver?Silver is a chemical element with the symbol Ag and atomic wide variety 47. categorized as transition steel, Silver is stable at room temperature.
Which substance is molecular?It is a molecular substance, that's a substance with or more atoms, the smallest gadgets of remember joined together via a covalent bond. A covalent bond is a hyperlink created via the sharing of electrons that holds these atoms collectively.
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Green light has a wavelength of 510 nm. What is the wavelength in meters?
Please help! I'm confused on a few of these, 100 points!
Lamark goes to a bowling alley to test his belief that rolling a bowling ball slowly will result in knocking down more pins. He gently rolls his bowling ball towards the bowling pins lined up at the end of the lane. The bowling ball stops in the middle of the lane without striking the pins. Which statement below best explains what happened?
Answer:
The ball's kinetic energy is transforming to potential energy.
Explanation:
the ball is stopping resulting in potential energy
The degree of unsaturation, or index of hydrogen deficiency, is the number of pi bonds plus rings in a molecule. Specify the degree of unsaturation (index of hydrogen deficiency) of the following formulas:
(a) C5H6
(b) C10H6Cl2
(c) C4H3NO
Explanation:
The degree of unsaturation is given as;
Degree of unsaturation = (2C + 2 + N - H - X) / 2
(a) C5H6
Using the formular above;
Degree of unsaturation = [ 2(5) + 2 - 6] / 2
Degree of unsaturation = [ 12 - 6 ] / 2 = 3
(b) C10H6Cl2
Using the formular above;
Degree of unsaturation = [ 2(10) + 2 - 6 -2 ] / 2
Degree of unsaturation = [ 22 - 8 ] / 2 = 7
(c) C4H3NO
Using the formular above;
Degree of unsaturation = [ 2(4) + 2 - 3 -1 ] / 2
Degree of unsaturation = [ 10 - 4 ] / 2 = 3
Note: Oxygen is ignored because its presence has no effect on the degree of unsaturation.
1) Why does polysubstitution frequently occur with Friedel-Crafts alkylation but not with Friedel-Crafts acylation?2) If Benzene is reacted with t-butyl chloride, why is the chief disubstituted product the para rather than ortho isomer?
Answer:
See explanation
Explanation:
Friedel-Crafts alkylation frequently undergo polysubstitution because the process leads to the addition of an electron donating alkyl group, which activates the benzene ring to further alkylation. The acyl group rather deactivates the ring towards electrophilic substitution.
When benzene is reacted with t-butyl chloride, the chief disubstituted product is the para rather than ortho isomer because the increased bulk of the tert-butyl group hinders attack at the ortho-sites.
What is the difference between a pure substance and a mixture? Explain and give an example of each.
Answer: Matter can be broken down into two categories: pure substances and mixtures. Pure substances are further broken down into elements and compounds. Mixtures are physically combined structures that can be separated into their original components. A chemical substance is composed of one type of atom or molecule :)!
Calculate the volume in ml of a 0.555 M NaHCO3 solution that contains 14.7 g of NaHCO3. ______ ml
Answer:
315 mL
General Formulas and Concepts:
[tex]Molarity=\frac{moles \hspace{3} of \hspace{3} solute}{liters \hspace{3} of \hspace{3} solution}[/tex]
Explanation:
Step 1: Define variables
0.555 M NaHCO₃
14.7 g NaHCO₃
Step 2: Define conversions
Molar Mass of Na - 22.99 g/mol
Molar Mass of H - 1.01 g/mol
Molar Mass of C - 12.01 g/mol
Molar Mass of O - 16.00 g/mol
Molar Mass of NaHCO₃ - [22.99 + 1.01 + 12.01 + 3(16.00)] g/mol = 84.01 g/mol
1 L = 1000 mL
Step 3: Find moles of solute
[tex]14.7 \hspace{3} g \hspace{3} NaHCO_3(\frac{1 \hspace{3} mol \hspace{3} NaHCO_3}{84.01 \hspace{3} g \hspace{3} NaHCO_3} )[/tex] = 0.174979 mol NaHCO₃
Step 4: Find amount of solution
[tex]0.555 \hspace{3} M \hspace{3} NaHCO_3=\frac{0.174979 \hspace{3} mol \hspace{3} NaHCO_3}{x \hspace{3} L}[/tex]
[tex]0.555 \hspace{3} M \hspace{3} NaHCO_3(x \hspace{3} L)=0.174979 \hspace{3} mol \hspace{3} NaHCO_3[/tex]
[tex]x \hspace{3} L=\frac{0.174979 \hspace{3} mol \hspace{3} NaHCO_3}{0.555 \hspace{3} M \hspace{3} NaHCO_3}[/tex]
[tex]x \hspace{3} L=0.315278[/tex]
Step 5: Convert
[tex]0.315278 \hspace{3} L(\frac{1000 \hspace{3} mL}{1 \hspace{3} L} )[/tex] = 315.278 mL
Step 6: Simplify
We are given 3 sig figs.
315.278 mL ≈ 315 mL
A major component of gasoline is octane (C8H18). When octane is burned in air, it chemically reacts with oxygen gas (O2) to produce carbon dioxide CO2 and water H2O. What mass of carbon dioxide is produced by the reaction of 7.58 g of octane? Please explain the answer to me like I'm five, I want to understand but the content makes no sense.
Answer:
Mass = 23.232 g
Explanation:
Given data:
Mass of C₈H₁₈ = 7.58 g
Mass of CO₂ produced = ?
Solution:
Chemical equation:
2C₈H₁₈ + 25O₂ → 16CO₂ + 18H₂O
Number of moles of octane:
Number of moles = mass/molar mass
Number of moles = 7.58 g/ 114.23 g/mol
Number of moles = 0.066 mol
Now we will compare the moles of CO₂ with octane from balance chemical equation.
C₈H₁₈ : CO₂
2 : 16
0.066 : 16/2×0.066 = 0.528
Mass of CO₂ produced:
Mass = number of moles × molar mass
Mass = 0.528 mol × 44 g/mol
Mass = 23.232 g
Which statement best describes how to read a reaction pathway graph for an endothermic reaction?
A) Reactants absorb a minimum amount of energy and then release a larger amount of energy as products form.
B) Reactants release a minimum amount of energy and then absorb a larger amount of energy as products form.
C) Reactants absorb a minimum amount of energy and then release a smaller amount of energy as products form.
D) Reactants release a minimum amount of energy and then absorb a smaller amount of energy as products form.
Answer:
C) Reactants absorb a minimum amount of energy and then release a smaller
amount of energy as products form.
Explanation:
The statement that best describes how to read a reaction pathway from the graph of an endothermic reaction is that, reactants absorb a minimum amount of energy and then release a smaller amount of energy as products form.
In an endothermic change, heat is absorbed from the surrounding.
As such, the surrounding becomes colder at the end of the reaction. On a graph of an endothermic reaction, the reactants absorbs a minimum energy. As the reaction proceeds, the products gives off an even lesser amount of energy.Rocks that undergo weathering and emulsification result in which type of rock?
Igneous
Metamorphic
Sedimentary
Answer:
1st one
Explanation:
You have a carbonate buffer with pH 10.3 and a concentration of 2.0 M. What is the buffer capacity of 100 mL of the buffer against 3.0 M CsOH?
Answer:
Explanation:
pH = 10.3
[ H] = 10⁻¹⁰°³
= 5 x 10⁻¹¹ M
concentration of CsOH C = 3 M
pKa of carbonate = 6.35
Ka = 10⁻⁶°³⁵ = 4.46 x 10⁻⁷
Buffer capacity = 2.303 x C x Ka x [ H⁺] / ( Ka + [ H⁺]² )²
= 2.303 x 3 x 4.46 x 10⁻⁷ x 5 x 10⁻¹¹ / ( 4.46 x 10⁻⁷ + 25 x 10⁻²² )²
= 154 x 10⁻¹⁸ / 19.9 x 10⁻¹⁴
= 7.74 x 10⁻⁴ .
Is Kool-Aid dissolved in water in element compound or mixture?
Answer:
mixture
Explanation:
Kool-Aid is a mixture of sugar, water, dye, and flavoring.
Calculate the pH of a 0.46 M solution of NH 4Cl. ( K b for NH 3 = 1.8 × 10 –5)
a.
9.59
b.
4.41
c.
4.80
d.
0.34
e.
9.20
pH of the solution = 4.8
Further explanationNH₄Cl is a salt of a weak base and a strong acid so that it will be partially hydrolyzed
Reaction:
NH₄Cl -----> NH₄⁺ + Cl⁻
NH₄ will be hydrolyzed in water
NH₄⁺ + H₂O ------> NH₃ + H₃O⁺ (H⁺)
This solution releases H⁺ ions so they are acidic
Formula
[tex]\tt [H^+]=\sqrt{\dfrac{Kw}{Kb}.M }[/tex]
Kw = The water equilibrium constant = 10⁻¹⁴
Kb = the ionization constant of a base = 1.8.10⁻⁵
M = 0.46
[tex]\tt [H^+]=\sqrt{\dfrac{10^{-14}}{1.8.10^{-5}}\times 0.46 }[/tex]
[H+]=√2.55 x 10⁻¹⁰ = 1.599 x 10⁻⁵
pH = - log [H+]
pH = 5-log 1.599 = 4.796≈ 4.8
What does not represent a compound
Answer:
Every combination of atoms is a molecule. A compound is a molecule made of atoms from different elements. All compounds are molecules, but not all molecules are compounds. Hydrogen gas (H2) is a molecule, but not a compound because it is made of only one element.Explanation:
What elements make up amino acids? Look up the structures of the 20 amino acids in your textbook and list the 5 elements present.
Answer:
- carbon (C)
- hydrogen (H)
- oxygen (O)
- nitrogen (N)
- sulfur (S)
Explanation:
Amino acids are organic molecules which base chemical structure is composed by:
- a carbon atom (C)
- a carboxyl group (-COOH)
- an amino group (-NH₂)
- a side chain- called R group- which varies in different amino acids. It can be composed by N, H, O, C and sometimes S.
According to this, the five chemical elements that are present in amino acids are:
- carbon (C)
- hydrogen (H)
- oxygen (O)
- nitrogen (N)
- sulfur (S)
Which of the following are true regarding a metamorphic rock?
Metamorphic rocks must go through emulsification
Metamoprhic rocks melt into lava then cool down
Metamorphic rocks form through heat and pressure
Metamorphic rocks melt into magma then cool down
Answer:
metamorphic rock from heat and pressure
Describe three factors that could limit the growth of the prairie dog population
Answer:
Changes in environment, food source changes and disease?
Explanation:
I dont know what the answer choices are
Answer:
changes in the environment
Explanation:
like digging big holes.
Hope this helps!
