Answer: A
Explanation:
The white Dwarfs are a group of stars that are extremely bright and hot. Hence option A is correct.
What are stars?Stars are defined as any large gaseous heavenly body that emits light as a result of its own internal energy sources. Stars are celestial bodies that generate their own energy through the fusing of gases. They resemble bright orbs that burn gas and produce energy. Our solar system's star, the Sun, generates energy through the fusion reaction in which helium transforms into hydrogen.
When a white dwarf first forms, it is extremely hot, but because it has no energy source, it will gradually cool as it emits its energy into space. This implies that the color temperature of its radiation, which is initially high, will gradually decrease and turn red. After using up all of their nuclear fuel, stars like the Sun become white dwarfs.
Thus, the white Dwarfs are a group of stars that are extremely bright and hot. Hence option A is correct.
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what did you learn in chemistry?
Do you notice a pattern in the charge for elements in each group? Explain.
(Hint: relate to number of valence electrons and the octet rule)
Answer:
Below are some patterns in the charge for elements in each group.
Group 1 elements : 1 valence electron and form ions with charge +1
Group 2 elements : 2 valence electrons and form ions with charge + 2
Group 3 elements : 3 valence electrons and form ions with charge + 3(there are some exceptions as well)
Elements in groups 4 and 5 are unpredictable also the D block elements consist of multiple oxidation states..
Group 6 elements : 6 valence electrons, form ions with charge -2
Group 7 elements: 7 valence electrons, form ions with charge -1
The octet rule is being followed, the elements form either ionic bond or covalent bond to fulfill it.
eg: when a K atom forms a K+ ion, the ion has the same electron configuration as the noble gas Ar (argon).
When an O atom gains 2 electrons to form the O²⁻ ion, the ion has the same electron configuration as the noble gas Ne (neon).
Note: Boron (B) is in Group 3 but doesn't form ions.
A noticeable pattern in the charge for elements in each group of the periodic table is that: Elements in the same group have the same charge.
Discussion:
The pattern in the charge for elements in each group is characterized by the adoption of the same charge for elements in the same group irrespective of the period they are situated in.
An example is evident in the alkali metal, halogen and alkali Earth metals group.
The alkali metals lose their only Valence electron, to assume the octet configuration of the preceeding noble gas.
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Which process in the atmosphere is responsible for moving heat from warm equatorial regions to higher latitudes
Answer:
Heat transfer in the atmosphere from the equatorial regions to higher latitudes occurs through the process of Convection
Explanation:
The equatorial regions of the earth's surface receive the most heat from the sun than any other region of the earth. This is because the are most directly in line with the direct heat from the sun.
Due to this heat from the sun, atmospheric air around the equatorial regions are hot and less dense than air in regions of higher latitudes, and thus, rises above the equator. The rising air at the equator is replaced by colder and denser air from higher latitudes north and south of the equator. As the rising air of the equatorial regions are being replaced by colder and denser air from higher latitudes, the hot and humid air moves away from the equator, toward regions of higher latitude, north and south thereby setting up a convection current of heat flow.
5. Water has a specific heat of about 4 J/Kg. It has a heat of fusion
of about 330 J/g. A 100-g ice cube is added to'a container with 400 g of room temperature (25°C) water. Is the final 500 g of water
A. below 0°C
B. slightly above 0°C
C. close to 25°C
D. near the middle of 0°C and 25°C
Answer:
The answer is slightly above 0°C.
Explanation:
The ice melts and absorbs 330 J/g × 100 g = 33000 joules.
Cooling 400 g of water from 25°C to 0°C requires
4 J/K-g × 400 g × 25°C = 40000 joules
The heat taken to melt is almost enough to cool the water all of the way to 0°C.
The answer is slightly above 0°C.
In a thermonuclear device, the pressure of 0.5 liters of gas within the bomb casing reaches 4.0 x 10^6 atm. When the bomb casing is destroyed by the explosion, the gas is released into the atmosphere where it reaches a pressure of 1.00 atm. What is the volume of the radioactive gas after the explosion?
please help for the love of god
Answer:
Great Rapids White Water Rafting Company rents rafts for $125 per hour. Explain why the point, (0,0) and (1, 125) are on the graph of the relationship and what these points mean in the context of the problem. * 100 points
Explanation:
Which phrase most accurately describes a chemical change?
Question 3 options:
A change on the molecular level.
A change in appearance.
A change in taste.
A change in form.
The phrase that most accurately describes a chemical change is; "A change on the molecular level."
The major difference between a physical change and a chemical change is that a chemical change involves a change in the composition of a substance.
This implies that the atoms in a substance are rearranged during a chemical change.
This rearrangement of atoms corresponds to change on a molecular level.
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What happens to the temperature and density of the material between points B and C?
Answer:
Temperature decreases and density increases
Explanation:
Let us remember that density of a material increases as the temperature of the material decreases. So the cooler a material becomes, the denser it becomes also.
Between points B and C, the material rapidly cools down and the temperature decreases accordingly. This ultimately results in an increase in density since cooler materials are denser than hot materials.
The type of response when a plant moves away from the stimulus
Answer:
A tropism is a turning toward or away from a stimulus in the environment. Growing toward gravity is called geotropism. Plants also exhibit phototropism, or growing toward a light source. This response is controlled by a plant growth hormone called auxin.
Explanation:
Screenshot very easy
Answer:
1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d⁶
Explanation:
Iron is soft, bright white metal.
Its symbol is Fe, atomic number is 26 and atomic mass is 55.85 amu.
It is present in group 8 of periodic table.
It is used to make the steel.
It is malleable and ductile used to make the sheets.
It is good conductor of heat and electricity because of moveable electrons that can easily move from one to another atom.
Its density is 7.87 g/cm³.
Electronic configuration:
Fe₂₃ = 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d⁶
Abbreviated electronic configuration:
Fe₂₃ = [Ar] 3d⁶4s²
Potassium chlorate (KClO3) decomposes in a reaction described by this chemical reaction:
2KCIO3( s) - 2KCI( s) + 302(g)
How does the reaction affect oxygen atoms?
A. The reaction changes 2 chlorine atoms into 2 oxygen atoms.
B. The reaction creates 3 oxygen atoms per formula unit of potassium chlorate.
C. The reaction changes their bonds, but neither creates nor destroys them.
D. The reaction creates 6 oxygen atoms per formula unit of potassium chlorate.
1. Explain redshift?
2. What is the Big Bang Theory? Explain why redshift is evidence for this theory.
(PLSSS HEELP)Which landform is created by wind?
Delta
Desert gravel
Horns
Oxbow lake
describe a chemical test for water. Give the test and the result
Answer:
Pure copper(II) sulfate is white. It is also known as anhydrous copper(II) sulfate because it has no water in it.
When water is present in a sample of copper(II) sulfate it turns blue. It is still a dry solid, because the individual water molecules are trapped within the ionic lattice surrounding the copper(II) ions. Solutions of copper(II) sulfate are also blue.
This colour change can be used to detect the presence of water (or water vapour).
Question 3 (10 points)
James is trying to calculate the wavelength of a wave. The frequency of the wave is 10 Hz and the speed of the wave is 50 m/s. What is the
wavelength? Show your work.
M
Frequency and wavelength are inversely proportional to each other. The wave with the greatest frequency has the shortest wavelength. Twice the frequency means one-half the wavelength. For this reason, the wavelength ratio is the inverse of the frequency ratio.
how do ions impact your life
Answer:
Increasing your concentration of negative ions is a very important way to improve your health for a variety of reasons. They work to increase serotonin levels in your body, which improves mood and balances your mental health, helping combat depression and anxiety.
Explanation:
Can someone help me please?
Answer:
I did this already
................
In what way would one dozen elephants and one dozen doughnuts be different?
the word dozen and the number 12 that makes a dozen
Can someone please help me out?
Answer:
c
Explanation:
How to find valency?
Answer:
ork out which of the displacement (S), initial velocity (U), acceleration (A) and time (T) you have to solve for final velocity (V).
If you have U, A and T, use V = U + AT.
If you have S, U and T, use V = 2(S/T) - U.
If you have S, U and A, use V = SQRT(U2 + 2AS)
if the percentage yield of a reaction is 85%
Answer: % yield
=
actual yield
theoretical yield
⋅
100
%
So, let's say you want to do an experiment in the lab. You want to measure how much water is produced when 12.0 g of glucose (
C
6
H
12
O
6
) is burned with enough oxygen.
C
6
H
12
O
6
+
6
O
2
→
6
C
O
2
+
6
H
2
O
Since you have a
1
:
6
mole ratio between glucose and water, you can determine how much water you would get by
12.0
g glucose
⋅
1 mole glucose
180.0 g
⋅
6 moles of water
1 mole glucose
⋅
18.0 g
1 mole water
=
7.20
g
This represents your theoretical yield. If the percent yield is 100%, the actual yield will be equal to the theoretical yield. However, after you do the experiment you discover that only 6.50 g of water were produced.
Since less than what was calculated was actually produced, it means that the reaction's percent yield must be smaller than 100%. This is confirmed by
% yield
=
6.50 g
7.20 g
⋅
100
%
=
90.3
%
You can backtrack from here and find out how much glucose reacted
65.0 g of water
⋅
1 mole
18.0 g
⋅
1 mole glucose
6 moles water
⋅
180.0 g
1 mole glucose
=
10.8
g
Explanation:
Answer:no answer,
Explanation: but if the other dude see this can you re word Wht u said it’s hard to make sense of it
i need help with gas law problems
What determines which element an atom is ?
The number of neutrons
The number of electrons
The size of the atom
The number of protons
The mass number of an atom is equal to the number of protons plus the number of neutrons that it contains. In other words, the number of neutrons in any atom is its mass number minus its atomic number.
hope this helps, if not, your free to give me 1 star
Jocelyn and her friends put some raisins, hazelnuts,
almonds, and peanuts in a bowl to make a snack for their
hiking trip. What does this snack represent?
A. a solution
B. a new element
C. a new compound
D. a mixture
plspslsspslpsl help its revision for exam and i need it quick brainliest for the right answer :D
Answer: D. a mixture
Explanation: When you mix different types of nuts or snacks together including raisins, hazelnuts, almonds, and peanuts to make some kind of trail mix, then you are creating a mixture, specifically a heterogeneous mixture.
which has less electron affinity? francium, strontium, silicon, or fluorine
Describe and explain one real-life and/or recent example of how scientific knowledge had to change or adapt in the face of new discoveries.
OR
Describe and explain one old (i.e. not accepted anymore...) scientific model or theory. Then, explain why or how that old model had to change.
Answer: Science is a particular way of knowing about the world. In science, explanations are restricted to those that can be inferred from confirmable data—the results obtained through observations and experiments that can be substantiated by other scientists. Anything that can be observed or measured is amenable to scientific investigation. Explanations that cannot be based on empirical evidence are not a part of science.
Explanation:
Answer:
Modeling can help scientists study things that they can’t directly observe. Plesiosaurs no longer exist. So, scientists can’t directly see how they moved their flippers. However, they can use existing evidence—the fossil structures of plesiosaurs—to bring these organisms to life in a computer model.
Explanation:
Sample but you can reword
if compose means to put together then decompose means to what?
Answer:
Break apart
Explanation:
Decompose: to break down or cause to break down into component elements or simpler constituents.
What is the relationship between plastic and gasoline?
Answer:
Explanation:
Both plastic and gasoline are products of pretroleum
How does thermal energy transfer when a room is heated by a furnace?
a
Hot air is absorbed by the objects in the room; cold air expands and rises.
b
Hot air is circulated through the room; the hot air rises, and cold air falls.
c
Hot air makes direct physical contact with the objects in the room and rises.
d
Hot air is transmitted by electromagnetic waves; the hot air rises and falls.
Answer: D is the right answer pls make me brainliest
Explanation:
Chris the chemist was working in the and he wanted to sou what would happen he put copper chloride into a Bunsen flameAs soon as it the , began 10 amit a green color Which of these BEST describes this outcome
The question is incomplete, the complete question is;
Chris the Chemist was working in the lab, and he wanted to see what would happen if he put copper chloride into a Bunsen burner flame. As soon as he put it in the flame, it began to emit a green color. Which of these BEST describes this outcome?
A) The heat split the nucleus and created a new element.
B) As the copper chloride was heated, electrons were turned into neutrons.
C) As the electrons moved to a higher energy level, a photon of light is emitted.
D) When excited electrons return back to the ground state, a photon of light is emitted.
Answer:
D) When excited electrons return back to the ground state, a photon of light is emitted.
Explanation:
According to Bohr's model of the atom, electrons may absorb energy and move up to higher energy levels.
These electrons quickly return to ground state from such higher energy excited states thereby emitting the excess energy absorbed during excitation.
If the higher energy level is E2 and the ground state is E1 then the energy of the photon emitted when the electron descends from energy level E2 to E1 is;
ΔE = E2 - E1
This photon emitted accounts for the green colour of the copper salt observed when it was heated.
Compounds X has the formula C7H15Cl; Y is C7H15Br. X undergoes base-promoted E2 elimination to give a single alkene product Z. Y likewise reacts under similar conditions to give a single alkene product that is isomeric with Z Catalytic hydrogenation of Z affords 3-ethylpentane. X readily reacts in SN2 fashion with sodium iodide in acetone. Y does not undergo a similar SN2 reaction. Propose structures for X and Y.
Answer:
See explanation and image attached
Explanation:
Let us examine the statements in the question carefully. First of all, we will discover that the products of the E2 elimination of the both compounds are isomeric. However Y does not undergo SN2 reaction as X does.
The fact that SN2 reaction does not occur in Y confirms that the bromine atom is attached to a tertiary carbon atom and SN2 reaction does not occur due to steric hinderance. Since X undergoes SN2 reaction in aprotic solvent, the chlorine atom must be attached to a secondary carbon atom.
However, E2 reactions does occur with tertiary alkyl halides when strong bases such as OH^- or RO^- are used.
The question also stated that the catalytic hydrogenation of Z affords 3-ethylpentane.
Putting all these together, the structures of X and Y have been suggested in the image attached to this answer.