Answer:
a
Explanation:
during witch age range do most girls bodies begin to grow hair under there under arms
select one of these options A. 5-9 b. 8-14 c. 15-18 d. 19-25 PLS HELP ASAP
Answer:
I think it's B, when hair begins to grow.
Explanation:
Good luck! <3
During photosynthesis, plants produce "food" for themselves. When animals eat plants, they take in energy that originally came from?
A.A seed
B. the soil
C. water
D. the sun
how many molecules are there in 24 grams of FeF3
Answer:
1.2x1023 molecules
hope this helped!
Explanation:
1227.6
Silicon has three naturally occurring isotopes. Based on the AVERAGE atomic mass, which is 28.085, what is the likely mass of the most common isotope
26
27
28
29
30
The most common isotope : Si-28, ²⁸Si
Further explanationThe elements in nature have several types of isotopes
Isotopes are elements that have the same Atomic Number (Proton)
Atomic mass is the average atomic mass of all its isotopes
In determining the mass of an atom, as a standard is the mass of 1 carbon-12 atom whose mass is 12 amu
An atomic mass unit = amu is a relative atomic mass of 1/12 the mass of an atom of carbon-12.
The 'amu' unit has now been replaced with a unit of 'u' only
Mass atom X = mass isotope 1 . % + mass isotope 2.% ..
The most common isotope is an isotope with a very large percentage which is indicated by the mass number closest to the average atomic mass
So from the above isotopes that are close to their average mass number is the Si-28
How does the scientist benefit society?
O A. The scientist uses specialized training to direct nonscientific
thought in society.
B. The scientist uses specialized training to tell society which
problems need to be fixed.
O C. The scientist uses specialized training to force governments to act
only in ways that benefit society.
D. The scientist uses specialized training to help solve problems
faced by society.
Answer: I believe it’s D
Explanation:
The following have been the main reasons for change in the scientific
views of the origin of the Universe over time:
O Technology
O Evidence
O The creation of new elements in a lab setting
Both Technology and Evidence
O All of the above
Answer:
all of the above
Explanation:
What is Kp for the reaction, 3 NO(g) ⇌ N2O(g) + NO2(g)
a) ∆H =-155.5 kJ/mol
b) ∆S =-171.5 J/mol K
c) ∆G =-104.4 kJ/mol
Answer:
For the reaction 3NO(g) ⇌ N2O(g) + NO2 (g) at equilibrium, Kp = 1.3×10^18 .
Explanation:
1s²2s²2p⁶3s²3p⁶4s²3d¹⁰4p⁴
Answer:
umm im just here for the points, im sorry if i knew i would answer it i dont take chemistry
Explanation:
A runner has a mass of 60 kg and a velocity of 0 m/s. What is her momentum?
Answer:
The answer is 0 kg m/sExplanation:
The momentum of an object can be found by using the formula
momentum = mass × velocity
From the question the momentum of the runner will be 0 kgm/s since the runner's velocity is 0
Hope this helps you
A student performs an investigation to determine which substance's addition to water, salt, or sugar would cause a greater increase in boiling point. Which step would the student complete after analyzing data? (2 points) Decide how much salt, sugar, and water to use in each of the tests Look on the Internet for ideas about types of tests to perform Predict whether a certain amount of salt or sugar will cause a greater increase State a conclusion about which substance increases the boiling point more
Answer:
State a conclusion about which substance increases the boiling point more
Explanation:
In scientific experiments, after the data has been collected and analyzed, valid conclusions can now be drawn from the analysis of data.
The process of experimental design involves;
i) observation
ii) formulation of hypothesis
iii)experiments
iv) analysis
v) conclusion
When the results are analysed and the hypotheses are tested, valid conclusions can now be drawn from data analysis.
In this case, analyzing the results show substances that increase the boiling point more than others.
The last column of the periodic table contains the noble gases, elements that do not easily form chemical bonds. why don’t these gases tend to form chemical bonds?
PLS HELPPP I WILL MARK BRAINLESY
An atom has 11 protons, 12 neutrons, and 10 electrons. What is the charge?
Answer:
The atom is Na, sodium with a net charge of +1 because it lost an electron. it usually has 11 electrons.
Explanation:
sodium has a 11 protons with an atomic mass of 23-11=12 neutrons.
To see the number of atoms of an element in a given molecule we need to multiply stoichiometry to the number that is written on the foot of the element that is stoichiometry. Therefore, the charge on atom is +1.
What is atom?Atom is the smallest particle of any element, molecule or compound. Atom can not be further divided. Atoms contains nucleus in its center and electron that revolve around the atom in fixed orbit.
In the nucleus, proton and neutron are present. Electron has -1 charge while proton has +1 charge. Neutron is neutral that is it has no charge. So overall the charge of nucleus is due to only proton, not by neutron.
Since the number of electrons is 10. The number of protons is 11. So, there is loss of one electron, so the charge on atom is +1.
Therefore, the charge on atom is +1.
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what is the hypothesis in the atomic dating game?
Answer:
it will fail
Explanation:
In an experiment, a model can help a scientist
A. test a situation that is otherwise too complex to observe
B. make the experimental setup match reality as closely as possible
C. create a hypothesis
D. draw a conclusion from experimental results
Answer:
B
Explanation:
the model is to represent something in reality
In an experiment, a model can help a scientist make the experimental setup match reality as closely as possible.
What is an experiment ?An empirical technique that settles conflicting models or hypotheses is called an experiment. Additionally, experiments are used by researchers to confirm or refute new or current theories.
Because experiments are used to verify a hypothesis, an axiom, or phenomena with a theoretical foundation in order to transform it into a law or a theorem like Newton laws, they play a crucial role in the progress of science.
Science uses experiments in many different ways. One of its key functions is to test hypotheses and serve as the foundation for scientific knowledge. It may also indicate the need for a new theory by refuting an established hypothesis or by revealing a new phenomenon that requires an explanation.
Thus, option B is correct.
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Petroleum ether followed by dichloromethane is used to separate fluorene and 9-fluorenone. Why would reversing the order in which these solvents are used be unwise
Answer:
9-fluorenone binds more strongly to the stationary phase.
Explanation:
9-fluorenone is more polar than fluorene because it possesses a carbonyl group. Recall that the stationary phase is alumina and alumina is a polar adsorbent. Alumina is a top choice for the separation of components that contain a weakly or moderately polar component. These polar components of the mixture are retained for a longer time and more selectively by the adsorbent.
The fluorene is eluted first with the Petroleum ether, this makes it easier to elute the 9-fluorenone with the dichloromethane. The 9-fluorenone will be slower because it is more strongly attracted to the alumina owing to its polar carbonyl group.
Fluorene moves faster because its' polarity is the same as Petroleum ether and also opposite of the alumina. If the order of solvents is reversed and dichloromethane is first used, the 9-fluorenone binds more strongly to the alumnina making it difficult to elute fluorene using Petroleum ether.
What is the half-life of radon-222 if a sample initially contains 120.0 mg and only 18.1 mg after 12.3 days?
Answer:
[tex]t_{1/2}=4.51days[/tex]
Explanation:
Hello.
In this case, since the kinetics of radioactive decay in terms of initial and final amounts, elapsed time and half-life is:
[tex]A=A_0\times2^{-t/t_{1/2}}[/tex]
we can compute the half time as shown below:
[tex]2^{-t/t_{1/2}}=\frac{A}{A_0}\\\\-\frac{t}{t_{1/2}} ln(2)=ln(\frac{A}{A_0})\\\\t_{1/2}=-\frac{t\times ln(2)}{ln(\frac{A}{A_0})}[/tex]
Plugging in the known amounts and elapsed time, we obtain:
[tex]t_{1/2}=-\frac{12.3\times ln(2)}{ln(\frac{18.1}{120})}\\\\t_{1/2}=4.51days[/tex]
Best regards!
What have scientists learned about the cuttlefish through observation?
A. The cuttlefish should not be hunted for food,
B. The cuttlefish got its name from an Old English word.
C. The cuttlefish was valuable to the Romans because it could
produce a brown ink.
O D. The cuttlefish can change its appearance to blend into its
environment.
Calculate the pH of the buffer that results from mixing 60.0 mL of 0.25 M HCHO2(pKa= 3.74) and 15.0 mL of 0.500 M NaCHO
Answer:
[tex]pH=3.44[/tex]
Explanation:
Hello.
In this case, since the formic acid (HCHO2) is a weak acid and it is mixed with its conjugate base (CHO2⁻) in the form of NaCHO2, we can compute the pH via the Henderson-Hasselbach equation:
[tex]pH=pKa+log(\frac{[Base]}{[Acid]} )[/tex]
Whereas the concentration of both acid and base are computed considering final total volume of 75.0 mL after adding the volume of each solution as shown below:
[tex]n_{base}=0.500mol/L*0.0150L=7.50x10^{-3}mol\\\\n_{acid}=0.25mol/L*0.0600L=1.5x10^{-2}mol[/tex]
And the resulting concentrations upon the final volume:
[tex][Base]=\frac{7.50x10^{-3}mol}{0.0750L}=0.1M[/tex]
[tex][Acid]=\frac{1.5x10^{-2}mol}{0.0750L}=0.20M[/tex]
Thus, the pH is:
[tex]pH=3.74+log(\frac{0.10M}{0.20M} )\\\\pH=3.44[/tex]
Best regards.
which diagram best represents the type of plate movement that results in the mountains
Answer:
I think it’s D.
Explanation:
The molar mass of M(OH)2, formed by the hypothetical metal M, is 199.416 g/mol. What is the molar mass of the corresponding sulfide?
Assume that the charge of the metal doesn't change.
Provide your answer in decimal notation rounded to two decimal digits (i.e. to the hundredths place).
Answer:
197.48 g/mol
Explanation:
We must first discover the relative atomic mass of M;
From;
M + 2[ 16 + 1 ] = 199.416
M + 34 = 199.416
M = 199.416 - 34
M= 165.416
Since the sulphide is MS
molar mass = 165.416 + 32.065
molar mass= 197.48 g/mol
The molar mass of the corresponding sulfide is 197.48 g/mol
Calculation of molar mass:Since The molar mass of M(OH)2, formed by the hypothetical metal M, is 199.416 g/mol.
Now the atomic mass of M should be
M + 2[ 16 + 1 ] = 199.416
M + 34 = 199.416
M = 199.416 - 34
M= 165.416
Since the sulphide is MS
So,
molar mass = 165.416 + 32.065
molar mass= 197.48 g/mol
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Calculate the concentration of vacancies in in fcc silver at 250oC given that the activation energyfor vacancy creation in silver is 79.5 kJ/mol. The units for your answer should be vacancies/cm3.
Answer:
The concentration of vacancies in fcc silver is [tex]6.6105\times 10^1^4 vacancies/cm^3[/tex]
Explanation:
Given is - silver (fcc lattice)
Temperature = 250°C = 523K
Activation energy for vacancy creation ,[tex]Q_v[/tex] =79.5 kJ/mol
Silver has a fcc crystal lattice structure with basis
Lattice parameter = 0.49nm = [tex]4.09\times 10^-^8[/tex]m
Now , let us calculate number of silver atoms"(lattice points)per [tex]cm^3[/tex]
[tex]N=\frac{4atoms/cell}{4.09\times10^-^8cm^3}[/tex]
=[tex]5.86\times10^2^2 Ag[/tex] atoms/[tex]cm^3[/tex]
Concentration of vacancies is given by the formula -
[tex]N_v =N_e_x_p\frac{-Q_V}{R.T_}[/tex]
here,
[tex]N_v = concentration of vacancies \\[/tex]
[tex]N= number of atoms[/tex] [tex]per[/tex] [tex]cm^3[/tex]
[tex]Q_v=[/tex] Activation energy for vacancy creation
T = Temperature
R = constant =[tex]8.314 J K^-^1 mole^-^1[/tex]
Now , putting the given values in the formula -
[tex]N_v= (5.85\times10^2^2atomscm^-^3)exp(\frac{-79.5KJ/mole}{8.314\timesJK^-^1mole^-^1})[/tex]
=[tex]6.6105\times10^1^4vacnacies/cm^3[/tex]
Hence , the answer is [tex]6.6105\times10^1^4vacnacies/cm^3[/tex]
Enzymes are potent catalysts because they: A. drive reactions to completion while other catalysts drive reactions to equilibrium. B. are very specific and can prevent the conversion of products back to substrates. C. are consumed in the reactions they catalyze. D. lower the activation energy for the reactions they catalyze. E. increase the equilibrium constants for the reactions they catalyze.
Enzymes are potent catalysts because they lower the activation energy for the reactions they catalyze (Option D).
What is a catalyst?A catalyst is any molecule capable of lowering the activation energy of a given chemical reaction, thereby making it possible in normal conditions.
Proteins called enzymes and specific types of RNA called ribozymes are well known due to their ability to bind substrates in a chemical reaction in order to generate one or more chemical products, which always require a certain amount of energy in order to carry out such chemical reactions.
Therefore, with this data, we can see that enzymes are biological catalysts capable of lowering the activation energy and thus carry out chemical reactions in normal cellular conditions such as for example, convert sugar glucose (i.e. a carbohydrate) into two molecules of pyruvate, which is a step of cellular respiration metabolic pathway.
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Predict the charge of the most stable ion of sodium
What would happen if a mixture of benzoic acid (C6H5CO2H) and chloroethane (CH3CH2Cl) is added to a separatory funnel containing H2O and CH2Cl2
Answer:
Both benzoic acid and chloroethane will be extracted into the CH2Cl2 layer. a small amount of the benzoic acid may be found in the water layer.
Explanation:
Both benzoic acid and chloroethane are more soluble in organic solvents. benzoic acid can only be soluble in water when it is converted into a benzoate.
Hence, only a small amount of the benzoic acid may be found in the water layer. Both benzoic acid and chloroethane are largely extracted into the dichloromethane layer.
The shark and remora have a relationship that benefits the remora but neither helps nor harms the shark What type of relationship is this
A student prepared a stock solution by dissolving 20.0 g of NaOH in enough water to make 150. mL of solution. She then took 15.0 mL of the stock solution and diluted it with enough water to make 65.0 mL of a final solution. What is the concentration of NaOH for the final solution?
A) O. 411 M
B) 0.534 M
C) 1.87 M
D) 2.43 M
Answer:
0.7692 M
Explanation:
[tex]m[/tex] = Mass of sample = [tex]20\ \text{g}[/tex]
[tex]V[/tex] = Volume of solution = [tex]150\ \text{mL}[/tex]
[tex]V_1[/tex] = Initial volume taken out of the stock solution = [tex]15\ \text{mL}[/tex]
[tex]Mo[/tex] = Molar mass of NaOH = [tex]39.997\ \text{g/mol}[/tex]
[tex]V_2[/tex] = Final volume of solution = [tex]65\ \text{mL}[/tex]
Molarity of stock solution is given by
[tex]M_1=\dfrac{m}{MoV}\\\Rightarrow M_1=\dfrac{20}{39.997\times 0.15}[/tex]
[tex]M_1V_1=M_2V_2\\\Rightarrow M_2=\dfrac{M_1V_1}{V_2}\\\Rightarrow M_2=\dfrac{\dfrac{20}{39.997\times 0.15}\times 0.015}{0.065}\\\Rightarrow M_2=0.7692M[/tex]
The concentration of NaOH for the final solution is 0.7692 M
How many protons, electrons, and neutrons does an atom with atomic number 50 and mass number 125 contain? *
can someone please help me it's already past due
Answer:
Q1: 4
Q2: 2
Q3: 2
Explanation:
1) Calculate the density of a rock with a mass of 267 grams and a volume of 968 cm?
Answer:
.2758 g/cm
Explanation:
density = mass / volume
267/968 = .2758
which element would have the highest ionization energy? Na, Mg, Al, P
Answer:
The first ionization energy varies in a predictable way across the periodic table. The ionization energy decreases from top to bottom in groups, and increases from left to right across a period. Thus, helium has the largest first ionization energy, while francium has one of the lowest.
Explanation: