Which of the following best describes how Thomson
concluded that electrons are present in all atoms.
a
The charge-to-mass ratio of electrons is always the
same constant, no matter which substances are
used in the cathode ray tube.
b The cathode ray was able to turn a wheel.
The cathode ray always bent toward a negatively
charged plate.
d
The charge-to-mass ratio is unique to each different
element.
Answer: A
Explanation:
The charge-to-mass ratio of electrons is always the same constant, no matter which substances are used in the cathode ray tube.
Explanation:
Thomson in his model of atom discussed that the atom consists of a negative charge particle termed electron randomly distributed in the positively charged sphere to balance the negative charge.His model of the atom was also known as the Plum pudding model of the atom. In which electrons are embedded in positive soup.He discovered electrons by conducting an experiment with cathode rays in which cathode rays emerging from the cathode were observed to be deflected towards the positively charged plate.He also conducted the same experiment with different metals (for anode and cathode) and gases and found out that the charge to mass ratio of the electron was regardless of the metals or gases used in the experiment.With this, he landed on the conclusion that these particles of cathode rays are the universal component of matter.So, from this, we can conclude that the charge-to-mass ratio of electrons is always the same constant, no matter which substances are used in the cathode ray tube describes Thomson's conclusion that electrons are present in all atoms.
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Un estudiante preparo 200 ml de solución de acetato de potasio (CH3COOH ; Masa molar = 98 g/mol ; Ka CH3COOH = 1,8 x 10-5), disolviendo 3,5 g de ácido, la que denomino "Solución A". Posteriormente preparo otra solución de menor concentración del mismo soluto que denomino "solución B" y para ello tomo un volumen de 5,5 ml de la solución A y agrego agua hasta 70 ml de solución. Señale el pH de solución A y B y, la concentración molar de CH3COO- en la solución b.
Answer:
mirar respuesta abajo
Explanation:
Muy bien. Antes de responder lo que piden en el problema, vamos a calcular la concentración inicial de la solución A:
1) Concentración de la solución A:
En este caso, se sabe que se usaron 3,5 g de la sal, se puede calcular los moles usando el peso molecular y la masa:
n = m/PM (1)
Aplicando tenemos:
n = 3,5 / 98 = 0,0357 moles
Conociendo los moles, podemos calcular la concentración:
M = n/V (2)
Aplicando la formula tenemos:
M = 0.0357 / 0.200 = 0.1785 M
Esta es la concentración del ácido etiquetado como "Solución A".
Ahora podemos ver la concentración de la solución B, para luego calcular las concentraciones molares de los iones en solución y sus respectivos pH.
2) Concentración del ácido en la solución B:
Con la concentración de "A", se puede determinar la concentración de la solución B. Aqui podemos esperar que sea un valor mas bajo, puesto que es una dilución la que estamos haciendo. Por lo tanto.
Si se toma 5.5 mL de la solución A, entonces:
n = 0.1785 * 0.0055 = 0.00098 moles
Con esto, se calcula la nueva concentración:
M = 0.00098 / 0.070 = 0.014 M
Esta es la concentración de la solución B. Ahora para calcular pH y concentraciones de los iones en equilibrio, hay que plantear la reacción acido base en equilibrio. Como es el mismo compuesto, usaremos la misma ecuación.
3) pH de las soluciones A y B:
Planteamos la reacción de equilibrio:
CH₃COO⁻ + H₂O <------> CH₃COOH + OH⁻ Kb
Calculando el Kb, sería asi:
Kb = Kw/Ka
Kb = 1x10⁻¹⁴ / 1.8x10⁻⁵ = 5.56x10⁻¹⁰
Ahora reescribimos la ecuación y hacemos una tabla de equilibrio:
CH₃COO⁻ + H₂O <------> CH₃COOH + OH⁻ Kb = 5.56x10⁻¹⁰
i) 0.1785 x x
eq) 0.1785-x x x
Kb = [OH⁻] [CH₃COOH] / [CH₃COO⁻]
Reemplazando nos queda:
5.56 * 10⁻¹⁰ = x² / (0.1785-x)
Y como Kb es muy pequeño, se asume que el valor de x será también pequeño, asi que podemos redondear la resta a simplemente 0.1785, quedando tan solo:
5.56 * 10⁻¹⁰ = x² / (0.1785)
x² = 5.56*10⁻¹⁰ * 0.1785
x = √9.9246*10⁻¹¹
x = 9.96*10⁻⁶ M
Esta es la concentración de [OH⁻] y [CH₃COO⁻] en la solución A.
Aplicando lo mismo para la solución B (Cambiando solo el dato de concentración) nos queda:
x = √5.56*10⁻¹⁰ * 0.014
x = 2.79x10⁻⁶ M = [OH⁻] = [CH₃COO⁻]Finalmente, para calcular pH, se calcula primero el pOH y luego el pH:
pH = 14 - pOH
pOH = -log[OH⁻]
Para la solución A:
pOH = -log(9.96*10⁻⁶) = 5
pH = 14 - 5
pH = 9En el caso de la solución B:
pOH = -log(2.79*10⁻⁶) = 5.55
pH = 14 - 5.55
pH = 8.45Espero te ayude
Kinetic molecular theory states... (choose all that apply)
A. There is a chemical change when a solid melts to a liquid.
B. Particles that make up matter have kinetic energy.
C. Particles that make up matter are always in motion
What is force and motion
Answer:
In physics, a force is any interaction that, when unopposed, will change the motion of an object. A force can cause an object with mass to change its velocity (which includes beginning moving from a state of rest), i.e., to accelerate. Force can also be described intuitively as a push or a pull.
lol
Which of the following is the correct model of C7H16?
A.
B.
C.
D.
Answer:
D
Explanation:
Option D gives the correct model of C7H16. From the option, one will discover that the model has 7 carbons in the backbone. If you count the attached hydrogen, you will discover that the hydrogen is 16 in total.
This model or skeletal structure of this element represents heptane. Heptane or n-heptane is known to be a straight-chain compound and an alkane. It's chemical formula can also be written as: H₃C(CH₂)₅CH₃ or C₇H₁₆.
This compound is known to be one of the main components of gasoline. It is known to be a volatile organic compound and a clear and colorless liquids with a petroleum-like odor.
Answer: D
Explanation: Just took the test
What volume will 250. mL of gas at STP occupy ig the pressure changes to 2.0 atmospheres and the temperature changes at 30 degrees Celsius
Answer:
it is 75 degrees
Explanation:
Volume is 138.7 mL.
The equation for calculation of volume is as follows:-
[tex]\frac{P_1V_1}{T_1} =\frac{P_2V_2}{T_2}[/tex]
STP:-
Temperature=273 K
Pressure=1 atm
[tex]\frac{1 atm\times250mL}{273 K} =\frac{2 atm\times V_2}{303\ K}\\V_2=138.7\ mL[/tex]
Hence, the volume is 138.7 mL.
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Name the gas evolved when Zn reacts with dil.HCI (choose the answer from the following)
1. O2 2. H2 3. CO2 4. Cl2
Answer:
H₂
Explanation:
a molecule for sulfur dioxide consists of one sulfur atoms (S) and two oxygen atoms (0). what is the chemical formula for this compound
Element X has two naturally occurring isotopes. The isotope with mass 62.93 amu has a
relative abundance of 69.2%. The isotope with mass 64.93 amu has a relative
abundance of 30.8%. Calculate the average atomic mass of Element X. What is the
identity of Element X?
3.58 x 1023 molecules of propane C8H8 would occupy how much space at STP
Answer: At STP, a mole of gas takes up 22.4 Liters. The 22.4 Liters/mole quantity can be derived from the Ideal Gas Law, PV = nRT, plugging in STP conditions for P and T, and solving for V/n, which gets 22.4 Liters/mole.
Explanation:
Which of the following elements are characterized by having full outermost s and p
orbitals?
F. Period 7
G.
Group 8A
H.
Inner transition elements
J.
Periods 4, 5, and 6
Answer:
Group 8A
Explanation:
Group 8A elements are characterized by having full outermost s and p orbitals. These elements are also known as the noble gases or inert gases. They occupy the last group on the periodic table.
They are known to have an outer shell configuration of ns² np⁶The configuration reveals that atoms of all the elements have completely filled orbitals in their outer shell sublevels. This accounts for the non-reactivity of elements in this group. Most of the elements in the group have high ionization energy and very low electron affinity values.Some of the elements in this group are Neon, Argon, Krypton, Xenon, and Radon.
Which statement best explains why the air pressure is greater at the poles than at the equator
Answer:
At the equator, the altitude is lower, and also because of the direct heating of sun rays on the surface, the temperature is much higher than at the poles. This makes the air near the surface hot and lighter and hence it rises up which results in lower air pressure.
Explanation:
Plz give me brainliest .-.
Michelle learns in science class that simple machines such as an inclined plane can change the amount of force needed to lift heavy objects. She decides to test this with an experiment.
Michelle chooses a 10 kg weight. She sets up a ramp made of smooth metal that makes an angle θ with the floor. She attaches a spring scale to the weight and the top of the ramp in order to hold the weight in place. She records the force from the spring scale, then changes θ and records it again. She repeats this several times.
In this experiment, what is the dependent variable?
A.
the mass of the weight
B.
the angle θ between the ramp and the ground
C.
the amount of force on the spring scale
D.
the material the ramp is made of
Be fast please
Electrons will pair up in an orbital only when
Answer:
All orbitals in the same sub level have one electron
Explanation:
All orbitals in the same sub level have one electron
list in the following elements in order of smallest to largest atomic radius. F, Cl, Br, l
And which has a larger atomic radius?
True or False: A Precipitate is a solid
that forms out of a liquid solution as a
result of a chemical reaction
Answer:
true because it undergoes a tranformation
Explanation:
Mark is in charge of making change at his family's garage sale on a hot summer day. He runs low on change and brings out a jar of pennies from the house. He keeps the lid off of the jar. Later in the day, he notices that the pennies are hot. Which statement best explains what happened?\
Answer:
This question is incomplete
Explanation:
The question is incomplete without the options. However, when a metal (in this case what the pennies are made of) is left in direct contact with the heat from the sun, it conducts this heat and becomes hot. This process is called thermal conduction. The thermal energy is readily accepted by the material in which the pennies are made of thereby increasing the thermal energy of the penny coin which then makes the pennies hot after being left under the sun.
What is Arsenic cost per unit?
Answer:
arsenic costs $320 per 100g
Explanation:
Would love some help pleaseee. and please at least read the question instead of skipping it please.
Measuring tools can have errors. Errors lead to ___________________ results and _______________ conclusions. To calculate the difference of the accepted value and the experimental value, scientists use this formula:
percent error = (experimental value − ) × 100. accepted value
Minimizing Bias
People show bias when they want everyone to accept their results. Bias can arise for many reasons:
• Companies show bias when they depict only the research details that are in the best interest of their ____________.
• Scientists may be biased toward their _____________ and modify results suit their needs.
• Scientists may also show to bias get their research published in ______________ ______________.
Such biases often lead to _______________ facts. An important part of scientific thinking is identifying biases and taking the necessary steps to minimize them.
For results to be considered scientifically accurate, any scientist, regardless of his or her own bias, should be able to replicate the experiment and get the same results.
Summary
Think of some studies you’ve heard about. How can you tell whether the studies were well-designed and scientifically accurate or had biases?
Answer: this looks like your homework
Explanation:if you want help you are going to have to ask a specific question instead of giving people your homework.
Answer:
Honestly I would search this up maybe there might be a pdf with the answers. Sorry chemistry isn't my thing:(
Explanation:
What explains the structure of metals and delocalized electrons?
A. the unit cell model
B. the geometric shape model
C. the covalent bond model
D. the electron sea model
A student decided to research primate psychology for their science project. They measured how long it took gorillas to adapt to their new habitat when moved from one zoo to another. They measured how long it took the new gorilla to interact regularly (more than 3 times per day) with the gorillas that already live there. Seven different cases were examined and the data collected. What can be said about the data? [GorillaTime to interact (days)12.523.138.343.352.763.273.4]
[
Gorilla 1 2 3 4 5 6 7 Time to interact (days) 2.5 3.1 8.3 3.3 2.7 3.2 3.4
]
A. The data is only measured to one decimal place, so it is not reliable.
B. The data falls within similar ranges so it may be reliable.
C. The data is reliable because there is only one outlier.
D. The data may not be reliable because there is an outlier.
Answer: the answer is D im pretty sure
Explanation:
True/False: Units for gas density are grams/L
Answer:
false
Explanation:
The bright red line from the emission spectrum of hydrogen has a wavelength of 657 nm. What is the energy, in joules, of a single photon of this light? 4.35 x 10–40 J 3.03 x 10–28 J 3.03 x 10–19 J 4.56 x 1014 J
Answer:
3.03 × 10^-19 J
Explanation:
The energy, E, of a photon of light can be calculated by using the formula:
E = hv
Where; E is energy in Joules,
h is Planck's constant {6.626×10^−34J}
v is frequency of light
For this question, the wavelength (λ) is given, not the frequency (v).
Hence, we use;
v= c/λ
Where v= frequency, c= speed of light (3×10^8m/s), λ= wavelength (657nm)
657nm = 657 × 10^-9m
v = 3×10^8/657 × 10^-9
v = 3/657 × 10^(8--9)
v = 0.00456 × 10^17
v = 4.56 × 10^14
Since frequency (v) = 4.56 × 10^14;
E = hv
E = 6.626×10^−34 × 4.56 × 10^14
E = 30.21 × 10^(-34+14)
E = 30.21 × 10^-20
E = 3.021 × 10^-19
Therefore, the energy of the photon of light is 3.02 × 10^-19 J
I need help with the 2nd part first gets brainlist
Answer:
7. 4H₂O
Elements: Hydrogen, Oxygen
Number of molecules: 4
Number of elements: 8 H, 4 O
Number of Atoms: 12
Explanation:
The elements are determined by the their symbol i.e. H = hydrogen.
The number of molecules is determined by the coefficient ( the number in front of everything, in this case 4).
The number of elements is determined by the coefficient and the subscripts. Multiply the coefficient by the subscript after each element. When there is no subscript, it is equal to 1. 4H₂ = 4x2 = 8; 4O = 4x1 = 4.
The number of atoms is all the individual elements added together. 8+4 = 12.
Help it’s for a test!!!!!!!!!!!How many moles are in 2.16 x 1023 atoms of magnesium?
A. 35.9 moles
B. .359 moles
C. 7.18 moles
D. 0.359 moles
E. 0.90 moles
Identify the property of the matter described below.
Alcohol floats on top of the water.
A-pH
B-conductivity
C-density
D-luster
Answer: C.
Explanation: Alcohol floats on oil and water sinks in oil. Water, alcohol, and oil layer well because of their densities, but also because the oil layer does not dissolve in either liquid. The oil keeps the water and alcohol separated so that they do not dissolve in one another. ... Water sinks because it is more dense than oil.
A mixture cannot be reversed back to it’s original properties (true or false)
Answer:
False
Explanation:
A mixture is composed of two or more substances that are combined through physical means. It has NOT undergo any changes in its chemical properties. So, even though its appearance change, it can be reverted back.
Answer:
That answer would be false.
Explanation:
Depending on the type of mixture, you can separate it and reverse it back to its original properties through filtration, evaporation, distillation, and chromatography.
stages of mitosis in order
Answer:
nucleus formed
prophase
metaphase
anaphase
telophase and cytokinesis
How do I do this problem???
Answer:
i believe it's c
Explanation:
my reason is that if you look at the electrons 2 is the most comm
What is the process whereby scientists check each other’s work?
A. defining the audience
B. conferencing
C. peer reviewing
D. writing
Answer:
peer reviewing
Explanation:
Its peer reviewing because there peers and there reviewing eachothers work
The process whereby scientists check each other’s work is peer reviewing.
What is peer group?Peer group are the groups of people of same age, same background with same interest.
In the peer reviewing process group of members will check, evaluate and correct each others work, which in turn help the members of the group to update their work.
Hence, option (c) is correct i.e. peer reviewing is the process whereby scientists check each other’s work.
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