A scientist wrote a report that communicates the steps he performed in an investigation, the data he gathered, and his conclusions. A second scientist used the report to carry out the same investigation. However, her results were very different. Are the results of the investigation described below valid? If not, what should the scientists do next? Explain your reasoning.
Answer:
yes, this is an acceptable practice in research.
Explanation:
Note that, having a different result in one's research does not imply it is automatically invalid. However, because there may have been some errors or limitations in the previous work by the male researcher, it is possible that the later results are more accurate, even though she used the same procedures. She may have been more careful when calculating her results.
Answer:
Since the results did not match, she should repeat the investigation again. If the data still cannot be replicated, then the results are not valid. In that case, the next step is to restart the process of inquiry from the beginning. An improved design might produce valid, repeatable results.
Explanation:
What entropy change is associated with the reversible phase change from 1.0kg of ice to water at 0 ° C?
Answer:
1200 J/K
Explanation:
The formula for the entropy associated with a reversible phase change is
[tex]\Delta S= \dfrac{q_{\text{rev}}}{T}[/tex]
1. Calculate q
For a reversible phase change like melting,
[tex]q_{\text{rev}} = m\Delta_{\text{fus}}H = \text{1000 g} \times \dfrac{\text{334 J}}{\text{1 g}} = \text{334 000 J}[/tex]
2. Calculate ΔS
[tex]\Delta S = \dfrac{q_{\text{rev}}}{T} =\dfrac{\text{334 000 J}}{\text{273.15 K}} = \textbf{1200 J/K}[/tex]
Question 2 (0 points)
A spinner is spun and a die is rolled. What is the probability
of spinning red with the spinner or rolling an odd number with the
die.
red
/yellow
blue
green
Answer:
The probability of spinning red with the spinner or rolling an odd number with the die is [tex]\dfrac{1}{8}[/tex]
Explanation:
Given that,
Total color in spinner = 4
Let the area of four parts is equal in the spinner.
We need to calculate the probability of spinning red
Using formula of probability
[tex]P(A) = \dfrac{Number\ of\ red\ color\ outcome}{Total\ number\ of\ colors\ in\ the\ spinner}[/tex]
Put the value into the formula
[tex]P(A)=\dfrac{1}{4}[/tex]
We need to calculate the probability of odd number of the die
Using formula of probability
[tex]P(B) = \dfrac{Number\ of\ odd\ digits\ outcome}{Total\ number\ of\ digits\ in\ the\ die}[/tex]
Put the value into the formula
[tex]P(B)=\dfrac{3}{6}[/tex]
[tex]P(B)=\dfrac{1}{2}[/tex]
We need to calculate the probability of spinning red with the spinner or rolling an odd number with the die
Using formula of probability of two events which is independent
[tex]P(A\ and\ B)=P(A)\times P(B)[/tex]
Put the value into the formula
[tex]P(A\ and\ B)=\dfrac{1}{4}\times\dfrac{1}{2}[/tex]
[tex]P(A\ and\ B)=\dfrac{1}{8}[/tex]
Hence, The probability of spinning red with the spinner or rolling an odd number with the die is [tex]\dfrac{1}{8}[/tex]
Which of these discoveries contradict components of Dalton’s atomic theory? Check all of the boxes that apply.
Explanation:
ATOMIC THEORY
Lesson 1 - Page 5
J.J. Thomson
In 1897, English physicist J. J. Thomson (1856–1940) disproved Dalton’s idea that atoms are indivisible. When elements were excited by an electrical current, atoms break down into two parts. One of those parts is a negative tiny particle, which Thomson called a corpuscle in 1881. The term electron was introduced in 1891 by G. Johnstone Stoney (1826-1911) as a way to describe a “natural unit of electricity.” Thomson envisioned these negative charges embedded into positive charges, like an English plum pudding. The plums were the electrons and the pudding was the positive matter.
Thomson's idea of an atom did not survive very long. English physicist Ernest Rutherford (1871–1937) studied the effects of bombarding thin gold foil with alpha particles. Alpha particles are helium atoms that have lost their electrons and are positive. Rutherford’s model had a nucleus, which occupied a very small area toward the middle, and was positive. He used the term proton for the positive particles. However, his electrons were moving on the outside of the nucleus in no definable manner in his model.
A is Dalton's Model; B is Thomson;
and C is Ruthford's model of an atom
Convert each of the following lengths to the units requested.
A. 17.3 m to kilometers.
B. 2.56 m to kilometers
C. 567 dm to meters
D. 5.13 m to millimeters
Answer:
A=0.173 Km
B=0.00256 km
C=56.7 m
D=5130 mm
Explanation:
first we need to know that
[tex]1km=1000m\\\\1dm=0.1m\\\\1000mm=1m[/tex]
so we can form the following
[tex]\frac{1km}{1000m}=1\\\\\frac{0.1m}{1dm} \\\\\frac{1000mm}{1m}[/tex]
so in A
[tex]17.3m\\\\=17.3m*1\\\\=17.3m(\frac{1km}{1000m} )\\\\=0.0173km[/tex]
in B
[tex]2.56m\\\\=2.56m*1\\\\=2.56m(\frac{1km}{1000m} )\\\\=0.00256km[/tex]
in C
[tex]567dm\\\\=567dm*1\\\\=567dm(\frac{0.1m}{1dm} )\\\\=56.7m[/tex]
in D
[tex]5.13m\\\\=5.13m*1\\\\=5.13m(\frac{1000mm}{1m} )\\\\=5130mm[/tex]
What is the formula for potassium iodite? How did you get it?
Answer:
KI
Explanation:
Chemical formulaI −Molar mass126.90447 g·mol−1Conjugate acidHydrogen iodideAlchemy is the process of trying to turn non-gold metals into gold. It was practiced hundreds of years ago by scientists who believed that with the right amounts of heat or chemical reactions, they could make gold. After years of experiments and observations, gold was never produced. Which best describes the practice of alchemy
Answer:
Alchemy is a practice of making gold from other metals.
Explanation:
Alchemy is a method which is practiced by the ancient scientists of Europe, Africa and Asia trying to produced gold from other metals. This method was failed to produced gold from metals and all scientist suggested that metals can not be converted into gold. Greeks were the people who presented the theory of alchemy in the first few centuries of CE.
Answer:
the answer is Alchemy was scientific because it included observations and experiments
Explanation:
i took the test
Which phase change absorbs energy? A. H2O (g) --> H2O (s) B. H2O (g) --> H2O (l) C. H2O (l) --> H2O (g) D. H2O (l) --> H2O (s)
Answer:
C. H2O (l) --> H2O (g)
Explanation:
Hello,
In this case, we need to remember that processes absorbing energy are those that have positive heat, it means, process that obtain energy from a certain source. In such a way, processes that need energy, in terms of phase chance are fusion, sublimation and evaporation, which are the change from solid to liquid, solid to gas and liquid to gas respectively. Therefore, for the given options, we can see that C. H2O (l) --> H2O (g) accounts for an evaporation process which actually absorbs energy.
Best regards.
La rapidez a la que cantan los grillos de árbol es de 2.0 ×102 veces por minuto a 27°C, pero es sólo de 39.6 veces por minuto a 5°C. A partir de estos datos, calcule la "energía de activación" para el proceso del canto.
Answer:
51096J/mol = Energía de activación para el proceso del canto
Explanation:
Podemos solucionar este problema usando una forma de la ecuación de Arrhenius:
[tex]Ln\frac{K_2}{K_1} = \frac{-Ea}{R} (\frac{1}{T_2} - \frac{1}{T_1} )[/tex]
Donde K representa la velocidad de reacción (En este caso, la velocidad a la que cantan los grillos), Ea es la energía de activación, R la constante de los gases (8.314J/molK) y T representa la temperatura absoluta de 1, el estado inicial y 2, el estado final.
Estado inicial: K1 = 2.0x10²; T1 = 27°C + 273.15 = 300.15K
Estado final: K2 = 39.6; t2 = 5°C + 273.15 = 278.15K
Reemplazando en la ecuación:
[tex]Ln\frac{39.6}{2.0x10^2} = \frac{-Ea}{8.314J/molK} (\frac{1}{278.15K} - \frac{1}{300.15K} )\\\\-1.6195 = \frac{-Ea}{8.314J/molK}*2.6351x10{-4}K{-1}[/tex]
51096J/mol = Energía de activación para el proceso del cantoWhat kind of mixture is spaghetti and meatballs? A) Solute B) Suspension C) Heterogeneous D) Homogeneous
Answer: C
Explanation:
Spaghetti and meatballs are Heterogeneous mixture. A heterogeneous mixture is a mixture that is not uniform in composition throughout the mixture.
What are heterogeneous mixtures?A heterogeneous mixture is one in which the composition is not uniform throughout.Vegetable soup is a diverse concoction. A spoonful of soup contains varying amounts of various vegetables and other soup ingredients. Concrete, oil, lettuce, and trail mix (no cement).There are numerous mixtures all around us. Soils are made up of a wide range of substances, and their compositions vary depending on the sample taken.The following scoop may contain earthworms, but it may also contain dirt and grass. Another example of a heterogeneous mixture is smog.This cloudy pollutant buildup is a combination of water and pollutants from gasoline and plastics combustion, possibly mixed with nitrogen oxide derivatives and ozone.To learn more about heterogeneous mixtures, refer
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Can anyone solve this please. I need this fastly
Answer:
Average atomic mass = 63.3896
Explanation:
Step 1: Find how much Cu-65 we have
1 - Amount of Cu-63 = Amount of Cu-65
1 - 0.6915 = Amount of Cu-65
Amount of Cu-65 = 0.305
Step 2: Find the average atomic mass of Cu
(0.6915 x 63) + (0.305 x 65) = Average atomic mass
(43.5645) + (19.825) = Average atomic mass
63.3895 = Average atomic mass
Therefore the average atomic mass of Cu is 63.3895 atomic mass units
A substance X is formed from an exhaustible natural resource . It is a black and thick liquid with an unpleasant smell .It is a mixture of 200 substances.Some of the products such as dyes,explosives,paints,perfumes etc. Are obtained using this resource.The substance X is
Answer:
crude oil
Explanation:
The substance X would be crude oil.
Crude oil is a non-renewable natural resource that is black and thick in appearance. It is a mixture of several products and these are often separated by a process known as fractional distillation.
Some of the products from the fractional distillation of crude oil include the premium motor spirit (petrol), automotive gas oil (diesel), kerosene, etc., and derivatives for the production of dyes, paints, perfumes, etc.
is 0.0410 M−1 s −1 . We start with 0.105 mol C2F4 in a 4.00-liter container, with no C4F8 initially present. What will be the concentration of C2F4 after 3.00 hours ? Answer in units of M.
Answer:
After three hours, concentration of C₂F₄ is 0.00208M
Explanation:
The rate constant of the reaction:
2 C2F4 → C4F8 is 0.0410M⁻¹s⁻¹
As the units are M⁻¹s⁻¹, this reaction is of second order. The integrated law of a second-order reaction is:
[tex]\frac{1}{[A]} =\frac{1}{[A]_0} +Kt[/tex]
Where [A] and [A]₀ represents initial and final concentrations of the reactant (C₂F₄), K is rate constant (0.0410M⁻¹s⁻¹) and t is time of the reaction (In seconds).
3.00 hours are in seconds:
3 hours ₓ (3600 seconds / 1 hour) = 10800 seconds
Initial concentration of C2F4 is:
0.105mol / 4.00L = 0.02625M
Replacing in the integrated law:
[tex]\frac{1}{[A]_0}= \frac{1}{0.02625} +0.0410M^{-1}s^{-1}*10800s\\\frac{1}{[A]_0}=480.9M^{-1}[/tex]
[A] = 0.00208M
After three hours, concentration of C₂F₄ is 0.00208MAn infrared wave has a wavelength of 0.00005 m. What is this wavelength in
scientific notation?
A. 5.0 x 10-6 m
B. 5.0 x 10-5 m
C. 5.0 x 10-4 m
D. 5.0 x 10-3 m
Can someone please help me fast!!
Answer:
B. [tex] 5 \times {10}^{ - 5}\: m [/tex]
Explanation:
[tex]0.00005 \: m= 5 \times {10}^{ - 5} \: m \\ [/tex]
A sample of neon effuses from a container in 38 s. The same amount of an unknown noble gas requires 77.5 s. What is the unknown gas?
Answer:
Krypton.
Explanation:
By Graham's Law:
Rate 1 / Rate 2 = sqrt M2 / sqrt M1
Molecular Mass for Neon is 20.18
so we have:
38 / 77.5 = sqrt 20.18 / sqrt x where x is the unkown gas.
sqrt x = 9.162
x = 83.94.
This gas is Krypton.
A sample of neon effuses from a container in 38 s. The same amount of an unknown noble gas requires 77.5 s. The unknown gas is krypton.
What is noble gas ?The noble gases are a group of chemical elements that share several characteristics. They are all monatomic, odorless, and colorless gases with relatively little chemical reactivity under normal conditions. Helium, neon, argon, krypton, xenon, and radioactive radon are the six types of noble gases that are found in nature.
Due to their filled valence shells (octets), which render them incredibly nonreactive, the noble gases (Group 18), which are found in the far right of the periodic table, were formerly known as the "inert gases."
Due to their fully filled outer electron shells and lack of propensity to react with other elements, noble gases which are most frequently found as monatomic gases rarely form compounds with other elements.
By Graham's Law ;
Rate 1 ÷ Rate 2 = sqrt M2 ÷ sqrt M1
The Molecular Mass for Neon is 20.18
Then,
38 ÷ 77.5 = sqrt 20.18 / sqrt x
where x is the unknown gas.
sqrt x = 9.162
x = 83.94.
This is Krypton gas.
Thus, The unknown gas is krypton which is noble gas.
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What did Henry Moseley contribute to the modern periodic table?
O A. He discovered the lanthanides and actinides.
O B. He identified all of the elements that are currently in the periodic
table.
O C. He ordered the elements based on atomic number.
O D. He ordered the elements based on atomic mass.
Answer:the answer c
Explanation: because he believes that properties of elemets are periodic function of there atomic number
Can someone pls explain this to be step by step:
The density of a substance is 1.03g/cm? What would be the density in mg/mm'?
Answer:
Explanation:
You can do this by doing dimensional analysis.
The first step is to change grams to mg
1000 mg = 1 gram
So the fraction will look like this
1.03 g * 1000 mg/ 1 gram = 1030 mg (the grams cancel out)
Now move onto the volume. The volume is actually 1 cm^3. This becomes 1 cm^3 / 1000 mm^3
So the answer becomes
1030 mg / cm^3 * ( 1 cm^3/1000 mm^3) The cm^3 cancel out
1030 mg / 1000 mm^3
1.030 mg/ mm^3
What units should be used when describing the density of oil?
Answer:
Generally, density is measured using he SI unit for measurement of density which is kg/m³ or the cgs units used to describe the density of a substance which is g/cm³
However, due to its nature (being composed of varying amount proportions of different compounds mixed together resulting in a variation of the density of naturally produced crude oil) of having different densities whereby the lighter oils are more easily processed than the heavier variety of oils, oil density is related to the quality of the oil and it is usually measures in API gravity as follows;
°API = (141.5/S.G.) - 131.5
Where;
API = American Petroleum Institute
S. G. = Specific gravity
As such the API gravity of fresh water with a S. G. of 1.0 has is 10 degrees
Explanation:
WILL AWARD BRAILIEST Which of the following best describes the particles inside a propane tank and inside a glowing neon sign? A: The particles in both are charged. B: The particles of both fill up the entire space available to them. C: The particles in the propane tank take limited space and those in the glowing neon sign are uncharged. D: The particles in the propane tank are charged and those in the glowing neon sign fill up the entire space available.
Answer:
it is A as both are always charged
Explanation:
Answer: A the particle is always charged
Explanation:
A leaky faucet can waste 3,000 gallons of water per year. Which of the following is correct to convert the water wasted to liters/month? [1 gallon = 3.8 liters]
a
Divide 3,000 by 3.8
b
Multiply 3,000 by 12
c
Multiply 3,000 by 3.8 and divide the result obtained by 12
d
Divide 3,000 by 3.8 and multiply the result obtained by 12
Answer:
c
Multiply 3,000 by 3.8 and divide the result obtained by 12
. What is the kinetic energy of a jogger with a mass of 65.0 kg traveling at a speed of 2.5 m/s?
Answer:
Kinetic energy=1/2mv^2.
1/2×65×2.5^2.
1/2×6.5×6.25.
1/2×40.625.
=20.3125Joules.
The branch of science which deals with the chemicals bond is called chemistry.
The correct answer is 20.3125J
The energy formed by the motion of particles is called kinetic energy. The formula is half of the product of the mass and velocity.
[tex]Kinetic\ energy=\frac{1}{2}mv^2.[/tex]
After putting the value:-
[tex]\frac{1}{2}*65*2.5^2.[/tex]
After solving the equation, the kinetic energy is 20.3125Joules.
Hence, the correct answer is 20.3125Joules.
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Which of the following best describes this sentence?
There were 20 flamingos at the zoo.
Group of answer choices
Qualitative observation
Quantitative observation
Qualitative inference
Quantitative inference
Answer:
i think quantitative observation
What is the mass, in grams, of 1.33 mol of water, H2O? Express the mass in grams to three significant figures.
Explanation:
First find the mass of 1 mole of water (Molecular mass)
[tex] H_{2} O = 2H + O [/tex]
[tex]
= 2(1) + 32 [/tex]
[tex]
= 34 \: grams
[/tex]
Hence 1 mole of water is 34 g
Compare
1 mole = 34 g
1.33 mole = x g
[tex] \frac{x}{34} = \frac{1.33}{1} [/tex]
[tex]
x = 1.33 \times 34 [/tex]
[tex]
\color{blue}{\boxed{x = 45.2}} \: \: \: \: to \: 3 \: s.f.
[/tex]
Therefore 1.33 moles of water is 45.2 grams
The mass of the substances can be given by the molar mass and the moles of the substances. The mass of 1.33 mole of water is expressed in grams as, 23.94 grams.
What is mass?The mass has been defined as the product of the moles of the substance and the molar mass in grams per mole. The mass is given in grams and has a formula,
Moles = mass ÷ molar mass
Mass = molar mass × moles
Given,
Moles = 1.33 moles
Molar mass of water (H₂O) is calculated as = 2 (1) + 16= 18 grams per mole
Using the formula of mole, mass is calculated as:
Mass = molar mass × moles
mass = 1.33 × 18
= 23.94 grams
The mass of the substance can be calculated if the value of the molar mass and the moles of the substance has been known. The molar mass of the substance can be calculated by adding the mass of the individual masses of the element in a molecule.
Therefore, 1.33 mol of water contains 23.94 grams.
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Which of the following pieces of lab equipment is used to protect eyes
Do objects with large masses always have large
weights? Explain
Answer:
No
Explanation:
No, as sometimes objects with large masses are very light since they aren't dense.
Zinc carbonate dissolves in water to the extent of 1.12 x 10-4 g/L at 25 C. Calculate the solubility product Ksp for ZnCO3 at 25 C.
Answer:
Ksp= 7.98 × 10^-13
Explanation:
According to the question, we are to calculate the solubility constant (Ksp) of Zinc carbonate (ZnCO3) in a dissolved solution.
The equilibrium of the reaction is:
ZnCO3 (aq) ⇌ Zn2+ (aq) + CO32- (aq)
According to this; 1 mole of Zinc carbonate (ZnCO3) dissolves to give 1 mole of Zinc ion (Zn2+) and 1 mole of carbonate ion (CO32-).
This illustrates that:
(Zn2+) = 1.12 x 10-4 g/L
(CO32-) = 1.12 x 10-4 g/L
However, 1.12 x 10-4 g/L is the solubility in mass concentration of ZnCO3, we need to convert it to molar concentration in mol/L by dividing by the relative molar mass of ZnCO3.
To calculate the molar mass of ZnCO3, we say:
Zn (65.4) + C (12) + 03 (16×3)
= 65.4+12+48
= 125.4g/mol.
Hence, molar concentration= 1.12 x 10-4 g/L / 125.4 g/mol
= 8.93 × 10^-7 mol/L.
Therefore;
Zn2+) = 8.93 x 10-7 mol/L
(CO32-) = 8.93 x 10-7 mol/L
Ksp = [Zn2+] [CO32-]
Ksp = (8.93 x 10-7) × (8.93 x 10-7)
Ksp = 7.98 × 10^-13
The principal, Mrs. Integer tells Mrs. Apex to write down exactly what she is doing step by step. In the scientific method this is called ... a the conclusion. b the data. c the hypothesis d the observation e the procedure
Answer:
E. the procedure
Explanation:
In scientific experiments, several steps are taken in order to achieve a significant result. However, the steps involved when performing the experiment should be taken note of and written down in a very comprehensible manner. The written step by step process involved in an experiment is called the PROCEDURE.
A procedure should be a guide to performing the experiment by a new experimenter. It should include everything done during the experiment. In this case, Mrs. Integer is telling Mrs. Apex to write down all she is doing during the experiment in a step by step manner. In essence, the principal is simply asking her to write a PROCEDURE.
Cite as principais características das tentativas de organização da Tabela periódica-Tríades de Dobereiner, o Parafuso Telúrico de Chancourtois e a Lei das Oitavas de Newlands.
Answer:
Todos os três cientistas classificaram os elementos de acordo com o peso atômico.
Explicação:
As características da Tabela Periódica da Tríade Dobereiner são as seguintes:
1. é uma das classificações mais antigas de elementos.
2. nesta classificação, o peso atômico de um átomo é igual à média dos outros dois pesos atômicos.
3. é baseado no peso atômico.
Características do parafuso telúrico de Chancourtois
1. É a primeira classificação baseada no peso atômico.
2. foi a primeira representação gráfica dos elementos da tabela periódica.
Características da Lei das Oitavas de Newlands
1. também organizou os elementos de acordo com o peso atômico.
2. Em uma linha há apenas sete elementos e o oitavo vem abaixo do primeiro elemento devido às mesmas propriedades físicas e químicas.
Given 1 in=2.54 cm, how many centimeters are in an average hand (9.50 inches) __ cm (3 significant figures)
Answer:
9.5 inches = 24.1 cm
Explanation:
Given that,
1 inch = 2.54 cm
We need covert 9.5 inches to cm. For this we will use unitary method. To convert 9.5 inches to cm multiply 2.54 and 9.5. So,
9.5 inches = (2.54 × 9.5) cm
9.5 inches = 24.13 cm
or
9.5 inches = 24.1 cm
Hence, this is the required solution.
The rate constant for a second-order reaction is 0.54 M-1s-1. What is the half-life of this reaction if the initial concentration is 0.39 M
Answer:
4.748 seconds
Explanation:
second-order is one in which the rate is proportional to the square of the concentration of one reactant. This can be expressed below;
2A----->P
Where
A is the reactant.
P is the product.
The rate can be expressed as
Rate= k[A]^2
Half-life reffers to time required to reduce the concentration of reactant to half of its initial value.
The half life of reaction can be calculated using below formula
Half-life =. 1/(K*I)
Where,
K = Rate constant = 0.54 1/ms
I = Initial concentration = 0.39 m
If we substitute these values we have
Half-life t(1/2) =1/(0.54×0.39)
=4.748 seconds
Therefore, the half life is 4.748 seconds