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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When solid sodium hydroxide (NaOH) pellets are dissolved in water, the temperature of the water and beaker rises. This is an example of ________
Answer:
Exothermic Reaction
Explanation:
The increase in temperature is as a result of the release of energy due to the dissolving of the NaOH pellets in water. This is an example of exothermic reactions.
They are easy to identify as the surroundings of the system becomes hot due to the release of the energy.
can someone please help me it's already past due
Answer:
Q1: 4
Q2: 2
Q3: 2
Explanation:
Imagine an element that has 15 protons, 16 neutrons, and 18 electrons. Which of the following would NOT be considered an isotope of this element? *
15 protons, 16 neutrons, and 15 electrons
15 protons, 17 neutrons, and 15 electrons
15 protons, 15 neutrons, and 18 electrons
Answer:
A: 15 protons, 16 neutrons, and 15 electrons
Explanation: An isotope of an element is when neutrons are taken away from the nucleus, or added to the nucleus.
If you change the amount of protons in the nucleus, not only will the charge become positive due to their being one more proton than an electron, but the atom will change to a new element, Sulfur. If you change the electron count, that will just affect how prominent the negative charge is on the atom, whether it be more negative by adding an electron, or more postitive by removing an electron. Therefore, the amount of neutrons that you add to the nucleus of an atom, will change the isotope of the atom, and that's why the answer is A because every other answer changes the neutron count other than A.
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.
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:
Predict the charge of the most stable ion of sodium
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.
how many molecules are there in 24 grams of FeF3
Answer:
1.2x1023 molecules
hope this helped!
Explanation:
1227.6
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
Which element is a nonmetallic liquid at room
temperature?
(1) hydrogen
(2) oxygen
(3) mercury
(4) bromine
Answer:
According to my research there are 2 answers present.
Explanation:
Bromine as well as mercury is a nonmetallic liquid at room temperature
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
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
The shark and remora have a relationship that benefits the remora but neither helps nor harms the shark What type of relationship is this
Solid calcium reacts with solid sulfur to produce solid calcium sulfide?
Answer:
Ca + S -----> CaS
Explanation:
Since it is balanced you don't need to multiply it any more.
Solid calcium reacts with solid sulfur to produce solid calcium sulfide. The balanced equation for this reaction can be given as Ca + S → CaS.
What is balanced equation?An equation for just a chemical reaction is said to be balanced if both the reactants as well as the products have the same number of atoms and total charge for each component of the reaction. In other words, both sides of a reaction have an equal balance of mass and charge.
The ingredients and outcomes of a chemical reaction are listed in an imbalanced chemical equation, but the amounts necessary to meet the conservation of mass are not specified. Solid calcium reacts with solid sulfur to produce solid calcium sulfide. The balanced equation for this reaction can be given as Ca + S → CaS.
Therefore, the balanced equation for this reaction can be given as Ca + S → CaS.
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1s²2s²2p⁶3s²3p⁶4s²3d¹⁰4p⁴
Answer:
umm im just here for the points, im sorry if i knew i would answer it i dont take chemistry
Explanation:
Which theory describes the way atoms are arranged within a molecule?
A. The scientific theory
B. The VSEPR theory
C. The Bohr atomic model
D. The atomic theory
Answer:
B. The VSEPR theory
Explanation:
The valence shell electron pair repulsion theory describes the way in which atoms are arranged within a molecule.
If an atom is bonded to two or more other kinds of atoms as in many covalent molecules and ions, the shape of the system is determined by the geometry of the bonds around the central atom. The variations in the bond angles of such molecules and ions can be explained by the valence shell electron pair repulsion model and hybridization. All electron pairs will orient themselves in such a way as to minimize the electrostatic repulsion between them.Answer:
B
Explanation:
The VSEPR theory
name the gas that is largely responsible for the acid rain phenomena
Answer:
sulfur dioxide
Explanation:
Why is it important to keep your fingers and hands away from your face while cooking?
Answer:
To prevent the spread of germs.
Explanation:
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:
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!
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
Which solution contains the fewest total ions?
400. mL of 0.10 M NaCl
300. mL of 0.10 M CaCl2
200. mL of 0.10 M FeCl3
800. mL of 0.10 M C4H10
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
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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How many valence electrons must a potassium atom lose to obtain a complete valence shell?
two
three
one
four
which diagram best represents the type of plate movement that results in the mountains
Answer:
I think it’s D.
Explanation:
How many hours will it take to fill a cubic vat of 18.7 fit edge length that has a density of 1.49 g/mL and is spilling at a rate of 3.85kg/s?
Answer:
It will take 19.9 hours to fill the cubic.
Explanation:
First, we can find the volume of the cubic.
[tex]V_{c}=18.7^{3}ft^{3}=6539.2 ft^{3}=1.85*10^{8} ml[/tex]
Let's multiple this volume times the density
[tex]V_{c}*\rho=1.85*10^{8} ml * 1.49 g/ml = 2.76*10^{8} g[/tex]
If we divide the spilling rate by V times density we will have:
[tex]t=\frac{V_{c}}{\rho R}=2.76*10^{5} kg/3.85kg/s=71688.3 s = 19.9 h[/tex]
Therefore, it will take 19.9 hours to fill the cubic.
I hope it helps you!
The study of chemicals and bonds is called chemistry. when the amount reactant and the product is equal is said to be equilibrium.
The correct answer is 19.9h.
What is density?The density, of a substance is its mass per unit volume.The formula used to solve the question is as follows:-
[tex]D= \frac{M}{V}[/tex]
The data is given as follows:-
[tex]V = 1.85*10^8\\[/tex]The density of the is as follows:-
[tex]V*D =1.85*10^8 *1.49 =2.76*10^8[/tex]
Hence, the time will be as follows:-
[tex]t=\frac{V_c}{Dr}\\ \\=\frac{2.76*10^5}{3.85} \\ = 71688.3s\\=19.9h[/tex]
Hence, the correct time is 19.9h.
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Use the balanced chemical equation to calculate the grams of HF that need to react with 4.44 g of SnF2. Express the mass in grams to three significant figures.
Answer:
Explanation:
SnF₂ + 2HF = H₂Sn + 4F
mol weight of SnF₂ = 156.7
mol weight of HF = 20
156.7 gram of SnF₂ reacts with 40 grams of HF
4.44 gram of SnF₂ reacts with 40 x 4.44 / 156.7 grams of HF
= 1.13 grams of HF .
A solution of potassium sulfide is mixed with a solution of magnesium bromide. Identify the two possible products.
A. MgBr
B. KS
C. K2S
D. K2Br2
E. MgBr2
F. MgS
G. KBr
Write the formula of the insoluble product from part 1. 8 KBr.
Answer:
G. KBr
F. MgS
MgS is the insoluble product.
Explanation:
When 2 salts as potasium sulfide, K₂S and magnesium bromide, MgBr₂ react, a double replacement reaction occurs where cations (K⁺ and Mg²⁺) exchange places, as follows:
K₂S + MgBr₂ → 2 KBr + MgS
Thus, the two possible products are:
G. KBr
F. MgS
Now, based on solubility rules:
All compounds containing alkali metal ions (As K⁺) are solubles in water. KBr is soluble
And all sulfides except calcium, strontium and barium sulfide are insoluble.
Thus, the insoluble product is:
MgS