The question is incomplete, The complete question is;
Scientists have changed the model of the atom as they have gathered new evidence. One of the atomic models is shown below. What experimental evidence led to the development of this atomic model from the one before it?
Answer:
A few of the positive particles aimed at a gold foil seemed to bounce back.
Explanation:
This model of the atom was proposed by Ernest Rutherford and was called the planetary model of the atom.
This model is based on an experiment using a gold foil on which alpha particles were focused. Most of the alpha particles passed through the foil. Some of the alpha particles were scattered at large angles and a few seemed to bounce back.
This led to the conclusion that the atom has a massive positive core around which electrons move as planets move around the sun.
Answer:
It is A
Explanation:
Choose the formula for calculating percent composition.
Answer:
The equation for percent composition is (mass of element/molecular mass) x 100.
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how does a allergy develop?
PLEASE HELP!
Answer: im not fully sure but from what i rememeber Allergies develop when your immune system mistakenly identifies a thing such as pollen, mold or food as harmful then your body reacts to it
Explanation:
Look carefully at the list of objects and order
them from smallest to largest.
ant
atom
cell
dust particle
ping pong ball
Explain why you have them in this order. Be sure
to use a 5 complete thoughts.
:
Answer:
Atom, cell, dust particle, ant, ping pong ball
Explanation:
Firstly, atoms make up all matter, including each of the items on that list. The only things smaller than atoms are the parts of the atom itself, protons, neutrons and electrons. Because none of those are on that list, atoms have to be the smallest. Next smallest is the cell. Cells are made up of atoms, but they also in part make up dust. You can see a dust particle with the naked eye, but in order to see a cell you must use a microscope. Thus, cells are smaller than dust particles. Next is an ant. Obviously, an ant is bigger than a speck of dust, and is made up of cells and atoms. Lastly all you have is the ping pong ball, which is much larger than the rest of the items. Hope this helps!
All matter, including each thing on the list, is made up of atoms. The protons, neutrons, and electrons that make up an atom are the only particles smaller than atoms.
Thus, Atoms must be the tiniest object because none of those are included in that list. The cell is the next smallest. Atoms make up cells, but dust also makes up a portion of them.
A dust particle can be seen with the unaided eye, but a microscope is required to see a cell.
Cells are hence smaller than dust particles. An ant comes next. Of course, an ant is composed of cells and atoms and is larger than a particle of dust.
Thus, All matter, including each thing on the list, is made up of atoms. The protons, neutrons, and electrons that make up an atom are the only particles smaller than atoms.
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What is the proper name for the chemical formula Cl4O5?
Answer:
Carbon tetraiodide
Explanation:
let me know if it works
Imran did an experiment to see how changing the
surface area of limestone affected the rate at which
it reacts with hydrochloric acid. He timed how long it
took for the reaction to produce 50 cm3 of carbon
dioxide gas. His results are shownin the picture
a) Explain why changing the surface area has the
effect that it does.
b) What must Imran have done to make this
experiment a fair test?
c) Write a word equation for this reaction (limestone
is calcium carbonate).
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The purpose of meiosis is to produce
A. Sex cells
B. Body cells
C. DNA
Answer:
A)sex cells
Explanation:
it’s the production of gametes, or sperm and eggs
What property allows objects to be subject to gravity?
friction
mass
inertia
acceleration
Answer:
Mass
Explanation:
A gas in a piston starts out with a volume of 156 mL, a temperature of 28.1° C, and a pressure of 1.12 atm. If it ends with a volume of 312 mL and a temperature of 87.2° C, what is the new pressure?
Answer:
0.67atm is the new pressure of the gas
Explanation:
To find one condition of a gas when pressure, volume and absolute temperature change we must use combined gas law:
[tex]\frac{P_1V_1}{T_1} =\frac{P_2V_2}{T_2}[/tex]
Where P is pressure, V is volume and T is absolute temperature of 1, initial state and 2, final state of the gas.
Replacing:
P₁ = 1.12atm
V₁ = 156mL
T₁ = 28.1°C + 273.15K = 301.25K
P₂ = ?
V₂ = 312mL
T₂ = 87.2°C + 273.15 = 360.35K
1.12atm*156mL / 301.25K = P₂*312mL / 360.35K
P₂ = 0.67atm is the new pressure of the gas
9. This type of bond consists of closely packed cations and loosely held valence e- rather than
neutral atoms.
a. lonic
b. Covalent
c. Metallic
d. polyatomic
Is hydrogen bond an attraction between polar molecules
Answer:
No because if there was an attraction hydrogen would not do it's function
HELP!!!!!!!!
One use of CaCl 2 to salt roads in the winter. The equation that describes the change in freezing point of a solvent due to a solute is T f =i x K f x molality. How much would the freezing point decrease if a 3.23 molal (m) solution were achieved? (K f =1.86^ C/(mol/kg) for water and i = 3 for CaCl 2 )
Answer:
On contact with ice, calcium chloride forms brine rapidly, which lowers the freezing point of water and melts snow and ice quickly. Calcium chloride forms brine faster than other ice melters because its hygroscopic properties actually cause it to attract moisture from its surroundings
Explanation:
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As stated in the article, “As Sticky as a Gecko . . . but Ten Times Stronger!,” the adhesive the researchers developed sticks best when it is pulled down parallel to the surface. What type of adhesion is this called?
The answer is Shear Adhesion, i just took the test on 21 edge.
Answer:
shear adhesion
Explanation:
edge
Shear adhesion sticks best when it is pulled down parallel to the surface.
What is shear adhesion?Shear adhesion is defined as the ability of tape due to which it resists the static forces which are applied in same plane as in backing.It is usually expressed in terms of time required by a given weight for an amount of tape to become loose from a vertical plane.
Molecular weight between two entanglements is the controlling factor of shear adhesion. Shear adhesion is affected by the following parameters which areas follows:
1)Tg of adhesive - Shear adhesion increases as Tg rises up to a certain temperature which is less than the room temperature.
2) Tan delta minimum value of adhesive- It is found that shear adhesion improves by an increase in tan delta minimum value.
3)Adhesive polarity- It is an important factor which affects adhesion such as tack,peel and shear.Adhesion performances are improved by introducing polar ingredients in the formulation.
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Balance the equation:
Answer:
3SiO2 + 2CaC2 ------> 3Si + 2CaO + 2CO2
Explanation:
Convert 6.24 x 10g to standard notation.
Answer:
3.45 x 10^5
Explanation:
No attempt was made to test sodium with hydrochloric
acid. Why not?
Answer:
the reaction is violent and quick
Explanation:
A mining crew extracted two different types of minerals from underground. Then, they transferred the same amount of energy into both minerals. Why did mineral A change while mineral B stayed the same? Explain what happened to the molecules of both minerals
Explanation:
A mining crew extracted two different types of minerals from underground. Then, they transferred the same amount of energy into both minerals. Mineral A changed and mineral B stayed the same phase because mineral B has a stronger molecular attraction than mineral A.
You start with 100mL of 14M HNO3 and 10grams of copper metal. How many moles of the nitrogen dioxide gas will be produced?
Answer:
0.316 moles are produced.
Explanation:
We state the redox reaction:
4HNO₃ + Cu → Cu(NO₃)₂ + 2NO₂ + 2H₂O
We need to determine the limting reactant:
0.1 L . 14 M = 1.4 moles
10 g . 1mol/ 63.54g =0.158 mol
Cu is the limiting reactant. Let's see
4 moles of acid need 1 mol of Cu to react
1.4 moles of acid may react to (4 . 1) / 1.4 = 0.35 moles
We do not have enough Cu.
1 mol of Cu can produce 1 mol of NO₂
Then 0.158 moles will produce, 0.316 moles. (double of moles)
If we see stoichiometry, ratio is 1:2
Match each term to its description. Match Term Definition Excess reactant A) Amount of product predicted to be produced by the given reactants Limiting reactant B) Reactant that can produce more of the product Theoretical yield C) Reactant that can produce a lesser amount of the product
Answer:
Excess reactant - Reactant that can produce more of the product
Limiting reactant - Reactant that can produce a lesser amount of the product
Theoretical yield - Amount of product predicted to be produced by the given reactants
Explanation:
In every chemical reaction, there is a limiting reactant and there is an excess reactant.
The limiting reactant determines the amount of product obtained. It is the reactant that produces a lesser amount of the product.
The excess reactant is known to be the reactant that produces a greater amount of the product.
The theoretical yield is calculated using the limiting reactant and is the amount of product predicted to be produced by the given reactants.
Why Doesn't The Earth Usually Feel Solar Winds?
Answer:
When the solar winds approach the Earth, the magnetosphere (part of the Earth's natural magnetic defenses) deflects/repels most of the charged particles and shields our planet's surface from the winds. Sometimes, however, the magnetosphere isn't strong enough to block the Earth from these winds, so they do hit Earth and may cause catastrophic consequences, such as ruin power grids, cut off telecommunications (cell service/calls), etc.
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PLEASE HELP!!!
How many kilograms of chlorine gas is needed to produce 45.0 grams of hydrochloric acid?
Answer:
43.76 g = 0.04376 Kg
Explanation:
The equation of the reaction is given as;
H2 + Cl2 --> 2HCl
From the equation;
1 mol of Cl2 produces 2 mol of HCl
Converting to mass;
Mass = Number of mol * Molar mass
Cl2;
Mass = 1 mol * 70.906 g/mol = 70.906 g
HCl;
Mass = 2 mol * 36.458 g/mol = 72.916 g
This means;
70.906 g of Cl2 produces 72.916 g of HCl
x g of Cl2 would produce 45g of HCl
70.906 = 72.916
x = 45
x = 45 * 70.906 / 72.916
x = 43.76g
1 pt
Vanadium (V) is element 23 on the periodic table. A sample contains 2.88x1022 atoms of V. Calculate the amount of V.
1 pt
x mol V
1 pt
Resubmit
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describe the three states of matter that are present when snow melts
Answer:
solid liquid and gas
Explanation:
ice is a solid then it melts to liquid and evaporates into gas
Answer:
Snow is basically water;
ice/snow is solid state
water is liquid state
vapour is gaseous state
Explanation:
Explain why it is often necessary to start a campfire with many pieces of kindling (small pieces of wood) rather than with a few large logs
Answer:
It is often necessary to start campfire with many pieces of kindling rather than large logs because it is easier to ignite smaller pieces than larger pieces. Imagine wanting to light up a pile of clothes and a small piece of a shirt. Which ignites faster? The piece of a shirt, because it is smaller and more likely to burn very quickly. Additionally, people criss-cross these tiny pieces of wood to enable more surface area and to allow more oxygen to pass through. As you know, oxygen is necessary for a flame to ignite.
What is the difference between a chemical symbol and a chemical formula?
Answer: A chemical symbol is a one- or two-letter designation of an element. Compounds are combinations of two or more elements. A chemical formula is an expression that shows the elements in a compound and the relative proportions of those elements. Many elements have symbols that derive from the Latin name for the element
Which cell organelle controls all cell activities? Group of answer choices B. Nucleus C. Cytoplasm D. Mitochondria A. Cell Membrane E. Cell Wall
SCIENCE
What is it called when two or more elements are brought together?
A. Solution.
B. Mixture.
C. Chemical reaction.
Answer:
C
chemical reaction .
Answer:
C
Explanation:
Chemical reaction.
chemical composition of the gas in LPG cylinder??
LPG is composed hydrocarbons containing three or four carbon atoms. The normal components of LPG thus, are propane (C3H8) and butane (C4H10). Small concentrations of other hydrocarbons may also be present.
Neon is a noble gas because it is stable non reactive and has ____ valence electrons
Answer:
8 .....................
20.What do carbon and silicon have in common?
a.They belong to the same column (family), therefore they have the same number of valence electrons.
b.They belong to the same column (family), therefore they have the same number of total electrons.
c.They belong to the same column (family), therefore they have the same number of energy levels.
d.They belong to the same column (family), therefore they have the samenumber of protons.
The carbon and silicon have in common that they belong to the same column (family), therefore they have the same number of total electrons. So, option B is correct.
What do carbon and silicon have in common?Carbon's closest analogue is silicon. Silicon and carbon are both tetravalent atoms that primarily form covalent (non-ionic) compounds. However, aside from the fact that both elements "can form four covalent bonds," there is surprisingly little in common between them.
Carbon has an atomic number of 6 and an electronic configuration of 2, 4. Silicon has an atomic number of 14 and an electronic configuration of 2, 8, 4. Because both elements have the same number of valence electrons, they are classified as being in the same group.
Thus, option B is correct.
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How many moles of Na2SO4 can be made with 7.28 mol of H2SO4?
Answer:
7.28 mol Na2SO4
Explanation:
Since it is already in moles, all we have to do is use a molar ratio
A molar ratio is the proportions of reactants and products using the balanced equation. When writing a mole ratio, the given information must cross out with the right thing.
7.28 mol H2SO4 * 1 mol Na2SO4/1 H2SO4 = 7.28 mol Na2SO4
*notice how the H2SO4 crosses out
