Which contribution is a modification to Thomson's plum pudding model?
A-Atoms are indivisible.
B-Electrons are scattered in an atom.
C-A positively charged nucleus sits at the center of an atom.
D-Atoms of the same element have the same properties.
Answer is: C) A positively charged nucleus sits at the center of an atom.
J.J. Thomson placed two oppositely charged electric plates around the cathode ray. He did experiments using different metals as electrode materials and found that the properties of the cathode ray remained constant no matter what cathode material he used.
Tomson concluded that atoms are divisible and that the corpuscles are their building blocks (atoms are made up of smaller particles).
J. J. Thomson discovered the electron in 1897.
His "plum pudding" model (1904) suggested: the electrons are embedded in the positive charge.
With this model, he abandoned his earlier hypothesis (the atom was composed of immaterial vortices).
Rutherford theorized that atoms have their charge concentrated in a very small nucleus.
This was famous Rutherford's Gold Foil Experiment: he bombarded thin foil of gold with positive alpha particles (helium atom particles, consist of two protons and two neutrons).
Rutherford observed the deflection of alpha particles on the photographic film and notice that most of alpha particles passed straight through foil.
That is different from Plum Pudding model, because it shows that most of the atom is empty space.
Answer:
C-A positively charged nucleus sits at the center of an atom.
Explanation:
The 'plum-pudding' model was put forth by J.J Thomson to explain the structure of an atom. According to the model, the electrons which are negatively charged particles are essentially dispersed in cloud of positive charges. This was later modified by his student Rutherford through the goil foil experiment.
Rutherford's experiment essentially suggested that the positive charges are concentrated in a core or the center of an atom while the electrons move around it in fixed orbits.
What about matter can change and what does not change according to the law of conservation?
Final answer:
The Law of Conservation of Matter states that the total mass of matter remains constant in a closed system, despite undergoing physical or chemical changes. In a nuclear reaction, there's a significant conversion between matter and energy, but the total content of matter and energy combined remains fixed.
Explanation:
The Law of Conservation of Matter is a fundamental principle in chemistry stating that the total mass of matter remains constant during any chemical change. Matter undergoes various transformations, such as a chemical change or a change in state from solid to liquid or gas. However, during these changes, the matter is neither created nor destroyed. The reconfiguration of atoms and the conversion of substances, such as during the brewing of beer or in the operation of batteries, illustrates this principle. In both examples, the mass and number of atoms before and after the reaction remain unchanged, embodying the conservation of matter.
However, when considering nuclear reactions, the scenario is different. Here, the energy changes are so vast that there is a measurable change in mass, showcasing a matter-energy conversion. This advanced topic aligns with the principle that the total quantity of matter and energy in the universe remains fixed. To summarize, whether considering the conversion of glucose to ethanol and carbon dioxide during brewing or the change in substances within a lead-acid car battery, the law maintains that matter can change form but is neither created nor destroyed in a closed system.
Students can use _________ to distinguish pure substances, such as elements and compounds with a constant composition, from other substances. A) color B) density C) particle size D) state of matter
Answer is: B) density.
Pure substance is made of only one type of atom or only one type of molecule, it has definite and constant composition with distinct chemical properties.
Mixtures are physical combinations of pure substances that have no definite or constant composition.
With constant composition density of pure substance is always the same and in other substances it can vary according the composition.
Density is a measure of mass per unit of volume.
The SI derived unit for density is the kilogram/cubic meter, but chemist usually use gram per cubic centimeter.
Where is most of the high-level waste from nuclear reactors stored?
WILL GIVE BRAINIEST.
the ocean
abandoned salt domes
at reactor site
natural caves
After analyzing rock core samples in an area with frequent earthquakes, many geologists believe a severe earthquake will occur in the area in the next 50 to 80 years. Other geologists, however, believe that such a prediction cannot be determined from the data collected. If these two groups of scientists have access to the same data, how can they form such different hypotheses?
A. Geologists manipulate data to fit their hypotheses, which results in different conclusions.
B. Scientific predictions must list every possible outcome to make sure that they are never incorrect.
C. Geologists have different specialties that can cause them to interpret data differently.
D. Scientific hypotheses need to be proven many times, so predictions of earthquakes are probably incorrect.
Answer: C. Geologists have different specialties that can cause them to interpret data differently.
Explanation:
The data is the outcome of a research study that is obtain after the implementation of the experimental methodology or by direct observation. The interpretation of data can vary among the scientists as they may have different perspective, knowledge and experience.
Thus according to the given situation, on the examination of rock samples in an area which exhibit frequent earthquakes, one type of geologists believe that a severe earthquake will occur and others believe that the prediction cannot be known by the data. This is indicating towards the fact that geologists in the given study may have different expertise, knowledge and perception which make them to interpret the data differently.
If 6.50 g of the unknown compound contained 0.217 mol of C and 0.433 mol of H , how many moles of oxygen, O , were in the sample?
Answer : The moles of oxygen in the sample was 0.216 mole.
Explanation : Given,
Moles of C = 0.217 mol
Moles of H = 0.433 mol
Mass of unknown compound = 6.50 g
Molar mass of C = 12 g/mol
Molar mass of H = 1 g/mol
Molar mass of O = 16 g/mol
First we have to calculate the mass of C and H.
[tex]\text{Mass of C}=\text{Moles of C}\times \text{Molar mass of C}[/tex]
[tex]\text{Mass of C}=0.217mol\times 12g/mol=2.604g[/tex]
[tex]\text{Mass of H}=\text{Moles of H}\times \text{Molar mass of H}[/tex]
[tex]\text{Mass of H}=0.433mol\times 1g/mol=0.433g[/tex]
Now we have to calculate the mass of oxygen.
Mass of oxygen = Mass of unknown compound - [Mass of C + Mass of H]
Mass of oxygen = 6.50 - [2.604 + 0.433]
Mass of oxygen = 3.463 g
Now we have to calculate the moles of oxygen.
[tex]\text{Moles of O}=\frac{\text{Mass of O}}{\text{Molar mass of O}}[/tex]
[tex]\text{Moles of O}=\frac{3.463g}{16g/mol}=0.216mol[/tex]
Therefore, the moles of oxygen in the sample was 0.216 mole.
If an atom’s mass number is 210 and its atomic number is 85, how many neutrons does it have?
Answer:
the answer is 125, i got this right
Match each base with its common use.
1.magnesium hydroxide A.laxative
2. sodium hydroxide B.soap
3. calcium hydroxide C.plaster
4. aluminum hydroxide D.deodorants
5. ammonium hydroxide E. household cleaner
Answer:
Many hydroxides find applications in everyday household items.
For example, Magnesium hydroxide is used as laxative. It can be consumed for this.
Sodium hydroxide is used as soap. The sodium hydroxide is melted, the essential oils are added and the soap is formed on cooling.
Calcium hydroxide is used as plaster.
Aluminium hydroxide is used as deodorant. It plugs the sweat pores to prevent more sweat.
Ammonium hydroxide is used as household cleaner. Ammonium hydroxide dissolves grease and other dirt.
Answer:
the answer is calcium hydroxide
Explanation:
cause it is bro trust me
Although you can see the pencil, it appears broken in the glass of water. This is because
A) electromagnetic waves cannot travel through solids.
B) electromagnetic waves travel at different speeds through different media.
C) electromagnetic waves compress more when they travel through denser media.
D) electromagnetic waves get closer together when they go through dense media like glass.
What is the symbol for molarity?
The mixture you separated was a mixture of iron filings, sand, and salt. Based on your understanding of matter, is this mixture a homogenous mixture or heterogenous mixture? How do you know?
homogenous mixture-the parts are not uniformly mixed
homogenous mixture-the parts are uniformly mixed
heterogenous mixture-the parts are not uniformly mixed
heterogenous mixture-the parts are uniformly mixed
how long does it take a snail travel a distance of 3ft at 0.1ft/sec
An amount of nitrogen undergoes a physical change and increases its volume. What can be known about this physical change?
Answer:
density changed would be the answer
Explanation:
Where should the author of a case study introduce the central question of the text?
The author of a case study should introduce the central question in the beginning of the text.
What is a case study?
Case study is an examination on a particular case, be it person, group, or event, in real world context. It will be based on a particular central question. So, the case study is mainly intended to answer the central question.
The central question is the question that can be asked about the topic in the first part of the case study.
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What are two main ways that minerals are classified
The two main ways that minerals are classified are :
Chemical compositionPhysical propertiesMinerals are classified based on the chemical composition ( chemical properties ) and physical properties which are usually the basis by which most substances in nature are classified as well.
Some of the chemical properties by which elements are classified are ; resistivity, conductivity and acidity while some physical properties by which minerals are classified includes , boiling point , shape and color .
Hence we can conclude that The two main ways that minerals are classified are Chemical composition, Physical properties
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which of these is an example of a chemical change?
A. Leaving Cheese out to get moldy
B. Smelling Sprayed perfume
C. Feeling the ice melt on your skin
D. Crushing ice with a hammer
Answer: A. Leaving Cheese out to get moldy
Explanation:
A physical change is defined as a change in which there is alteration in shape, size etc. No new substance gets formed in these reactions.
Example: Smelling Sprayed perfume : It is only diffusion of gas.
Feeling the ice melt on your skin: It is only change of state.
Crushing ice with a hammer: It is only change of shape.
A chemical change is defined as a change in which a change in chemical composition takes place. A new substance is formed in these reactions.
Example: Leaving Cheese out to get moldy : It involves oxidation of cheese to form new substances.
Thus Leaving Cheese out to get moldy is a chemical change.
The idea of arranging the elements in the periodic table according to their chemical and physical properties is attributed to
Examine the reactants of the incomplete synthesis reaction. 2Mg + O2 → __________.
Which of the answer choices correctly predicts the product of the synthesis reaction?
O2 + 2Mg
Mg + Mg + O2
2MgO
O2Mg
Answer: [tex]2MgO[/tex]
Explanation:
Synthesis reaction is a chemical reaction in which two reactants are combining to form one product.
According to the law of conservation of mass, mass can neither be created nor be destroyed. Thus the mass of products has to be equal to the mass of reactants. The number of atoms of each element has to be same on reactant and product side. Thus chemical equations are balanced.
[tex]2Mg+O_2\rightarrow 2MgO[/tex]
Thus the products of chemical reaction will be [tex]2MgO[/tex]
A teacher makes the following statement.
“Gasoline boils at a relatively low temperature (about 150°C). The kerosene is removed at around 200°C, followed by diesel oil at 300°C and fuel oil at around 370°C.”
What topic is the teacher most likely talking about?
distillation of a mixture
filtration of a pure substance
evaporation of a mixture
sorting of a pure substance
Answer:
Distillation of mixture.
Explanation:
Distillation is the process in which we separate the components of a mixture based on the boiling points.
The mixture is boiled and the components separates, lower boiling point substance separates first and then so on.
In petroleum refining fractional distillation is used.
In the given question teacher is talking about the distillation of gasoline or petroleum product.
A vertical column of elements in the periodic table is called a ...
The vertical columns on the periodic table are called groups or families.
Explanation:The vertical columns on the periodic table are called groups or families. Elements within the same group share similar chemical properties due to their identical outer electron configurations. There are 18 groups in the modern periodic table, each denoted by a number or a specific name.
Elements in the same group often exhibit comparable reactivity and bonding characteristics, providing a systematic way to understand and predict the behavior of elements. This grouping facilitates the organization of elements based on their shared characteristics and contributes to the periodic table's utility in chemistry.
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What is the symbol for molarity?
The answer in chemistry is mol/L and altho it is represented by the symbol M usually.
Answer:
the answer is "M"
Explanation:
capital M not lower m
List the Earth names for the 30 alien elements in order of atomic number
The earth names for the first 30 elements, in order of their atomic number (which is also equal to the number of protons in their nucleus), range from Hydrogen (1 proton) to Zinc (30 protons).
Explanation:The earth names for the 30 elements, in order of atomic number, include the following: Hydrogen (1 proton in its nucleus), Helium (2 protons), Lithium (3 protons), Beryllium (4 protons), Boron (5 protons), Carbon (6 protons), Nitrogen (7 protons), Oxygen (8 protons), Fluorine (9 protons), Neon (10 protons), Sodium (11 protons), Magnesium (12 protons), Aluminum (13 protons), Silicon (14 protons), Phosphorus (15 protons), Sulfur (16 protons), Chlorine (17 protons), Argon (18 protons), Potassium (19 protons), Calcium (20 protons), Scandium (21 protons), Titanium (22 protons), Vanadium (23 protons), Chromium (24 protons), Manganese (25 protons), Iron (26 protons), Cobalt (27 protons), Nickel (28 protons), Copper (29 protons), and finally Zinc (30 protons).
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fast pls..,.,,..,,.,.,.
If Earth was like a hardboiled egg, which part of Earth would the egg shell represent and why?
Crust, as its depth is up to 3,000 kilometers
Mantle, as its depth is up to 3,000 kilometers
Mantle, as its depth is less than 100 kilometers
Crust, as its depth is less than 100 kilometers
The part of the Earth that the shell of the hard boiled egg that would represent is ; ( D ) The crust as its depth is less than 100 kilometers
The shell of the hard boiled egg is the outermost part of the egg and it account for very little percentage of the overall volume of the egg just as the earth's crust is the outermost part of the earth which is also a component of the lithosphere and does not run deep into the Earth's mantle ( less than 100 kilometers).
Hence In Conclusion the part of the earth that the shell of the hard boiled egg that would represent is ; ( D ) The crust as its depth is less than 100 kilometer
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A student is trying to calculate the density of a ball. She already knows the mass, but she needs to determine the volume as well. Which of the following formulas can be used to calculate the volume of the ball?
V equals four-thirds times pi times r cubed
V equals one-third times pi times r squared times h
V = s3
V = πr2h
Answer:
A. V equals four-thirds times pi times r cubed
28) Air can be considered a mixture. Which statement helps describe air? A) Air contains a fixed ratio of atoms. B) The components of air separate into visible layers. C) The components of air can be separated by chemical means. D) The exact mixture of components varies from point to point.
Answer: The answer is D
Explanation:
A plant grows three inches in a month. Why is this a physical change?
A. The Size of a plant has changed
B. The plant makes energy from the sun to grow the flower
C. Heat of combustion from the sun helps the flower grow
D. Special structures in the plant react with sunlight to make the flower
The Size of a plant has changed is an example of physical change.
What is a physical change?
A physical change is a type of change in which the form of matter changes but the substance itself does not change. For instance, it can alter size or shape without causing a chemical reaction.
One or more chemicals can transform chemically into one or more new and distinct substances. Another name for it is a chemical reaction. As a result, it is clear that a chemical change is essentially a chemical reaction that involves atom rearrangement.
Therefore, The Size of a plant has changed is an example of physical change.
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A double replacement reaction can be best described as a reaction in which
A)a substitution takes place.
B)two atoms of a compound are lost.
C)ions are exchanged between two compounds.
D)electrons are exchanged between two atoms.
Option C= ions are exchanged between two compounds.
ExplanationA double displacement reaction, also known as a double replacement reaction or metathesis, is a type of chemical reaction where two compounds react, and the positive ions (cation) and the negative ions (anion) of the two reactants switch places, forming two new compounds or products. For example,
Na2S + 2HCl → H2S + 2NaCl
Option D is incorrect because electrons are exchanged between the atoms in oxidation –reduction reactions.
Answer:
C.) ions are exchanged between two compounds. Edge 2020.
in the formula for water (H2O) what does the subscript 2 indicate?
The subscript 2 indicates there are two hydrogen atoms in the compound
The number of atoms of any element in the given chemical formula is the number that is written on the foot of the symbol of that element. The total number of Hydrogen atoms is 2 which is written as subscript.
What is atom?Atom is the smallest particle of any matter. Atom combines to form element and element combine to form molecule or compound.
The total mass of atom is inside the nucleus. Inside the nucleus proton and neutron is there. So calculate mass of an atom, total mass of all protons is added to the total mass of neutron. Electrons revolve around the nucleus.
In our question, the number written on the foot of element Hydrogen in water H₂O is the number of atoms of Hydrogen. We can read the formula of water as one atom of oxygen react with 2 atom of hydrogen to make one molecule of water
Therefore the subscript 2 indicate the number of hydrogen atoms
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What contains pigments that absorb light energy