Answers
Giant stars' hydrogen reserves are almost depleted. High-mass stars are defined as having a mass of at least 8 times that of the Sun. These stars are of type O and B, and as we already observed, they only exist for a brief period of time on the Main Sequence, on the order of 10 million years.
Nevertheless, they go through very similar life phases to the low mass stars. Remember that these phases for low mass stars are: hydrogen burning in the core during the Main Sequence; when the hydrogen in the core is spent; the star starts hydrogen burning in a shell around the degenerate helium core; and the star moves up the Red Giant Branch.Extreme pressure increases the temperature to 100 million degrees, where helium burning is feasible, when the hydrogen fuel runs out. As the helium in the core is exhausted, the star starts burning helium in a shell around an inert carbon core while moving back up the H-R diagram to become a Red Supergiant. Suddenly, at the helium flash, the degenerate core starts burning helium and the star moves toward (but not quite to) the Main Sequence again.
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Related Questions
1.) Which line is pointing to the axon terminals?
2.) Which line is pointing to the cell body?
3.) Which line is pointing to the myelin sheath?
4.) Which line is pointing to the dendrites?
Answers
Answer:
1.) 5 or D
2.) 2 or B
3.) 4 or D
4.) 1 or A
Explanation:
I got them correct on the quiz on edge
8.0g of certain gas occupies 5.6 L at STP.
A) How many moles of gas are present?
B) What is the molar mass of the gas?
C) What is the common atmospheric gas was collected?
Answers
Answer:
A) Using the ideal gas law, we can calculate the number of moles of gas present:
```
PV = nRT
```
where:
* P = pressure (atm) = 1 atm
* V = volume (L) = 5.6 L
* n = number of moles of gas
* R = ideal gas constant = 0.08206 L atm / mol K
* T = temperature (K) = 273.15 K
Solving for n, we get:
```
n = (P * V) / RT
```
```
n = (1 atm * 5.6 L) / (0.08206 L atm / mol K * 273.15 K)
```
```
n = 0.25 mol
```
Therefore, there are 0.25 moles of gas present.
B) The molar mass of the gas can be calculated by dividing the mass of the gas (8.0 g) by the number of moles of gas (0.25 mol):
```
Molar mass = Mass / n
```
```
Molar mass = 8.0 g / 0.25 mol
```
```
Molar mass = 32 g/mol
```
The molar mass of the gas is 32 g/mol.
C) The common atmospheric gas with a molar mass of 32 g/mol is oxygen (O2). Therefore, the gas that was collected is oxygen.
Explanation:
6. How many moles are in 8.30 x 1023 molecules of CO₂?
a.
b.
C.
d.
1.37
2.8
55.5
100
Answers
an object has a mass of 14g and a volume 3.5 mL. what is the density of the object ?
Answers
Given :
Mass of object , M = 14 g .
Volume of object , V = 3.5 mL .
To Find :
The density of the object .
Solution :
Density of an object is given by :
\(Density=\dfrac{Mass}{Volume}\\\\\rho=\dfrac{M}{V}\\\\\rho=\dfrac{14}{3.5}\ g/mL\\\\\rho=4\ g/mL\)
Therefore , the density is 4 g/mL .
Hence , this is the required solution .
Is ice a food or a drink
Answers
Answer:
a drink my guy
Explanation:
just frozen
C c Why did they work an average brightness for each length of graphite tested?
Answers
An average brightness was calculated for each length of graphite tested to get a better understanding of the relationship between the length of the graphite and the brightness of the line it produced.
What is the use of graphite?Graphite has many uses in various industries. Some of its uses include: Pencils, Lubricants, Refractories, Batteries, Electrodes, Nuclear reactors, Aerospace industry.
By calculating the average, it is possible to see if there is a trend in the data and if longer or shorter lengths of graphite produce brighter or duller lines. This information can be useful in determining the best length of graphite to use for a particular task or project.
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3. A Wilkinson’s catalyst is widely used in the hydrogenation of alkenes. Show a catalytic cycle, including: i. chemical structure of the catalyst, with complete stereochemistry ii. molecular geometry of catalyst iii. type of reactions involved iv. the appropriate starting material, reagent and solvent v. major and minor end-products vi. all intermediates, for each reaction stated in (iii)
Answers
We can see here that the catalytic cycle for the hydrogenation of alkenes using Wilkinson's catalyst involves several steps.
What are the steps involved?Here's an overview of the catalytic cycle, including the necessary details:
i. Chemical structure of the catalyst:
Wilkinson's catalyst, also known as chloridotris(triphenylphosphine)rhodium(I), has the following chemical structure: [RhCl(PPh3)3]
ii. Molecular geometry of the catalyst:
The Wilkinson's catalyst has a trigonal bipyramidal geometry around the rhodium center. The three triphenylphosphine (PPh3) ligands occupy equatorial positions, while the chloride (Cl) ligand occupies an axial position.
iii. Type of reactions involved:
The catalytic cycle involves several reactions, including:
Oxidative addition: The rhodium center undergoes oxidative addition, reacting with molecular hydrogen (H2) to form a dihydride intermediate.Alkene coordination: The alkene substrate coordinates to the rhodium center, forming a π-complex.Hydrogenation: The coordinated alkene undergoes hydrogenation, resulting in the addition of hydrogen atoms to the double bond and formation of a metal-alkyl intermediate.Reoxidation: The metal-alkyl intermediate reacts with a hydrogen molecule to regenerate the rhodium dihydride species.iv. Starting material, reagent, and solvent:
The starting material is an alkene, and the reagent is Wilkinson's catalyst ([RhCl(PPh3)3]). The reaction is typically carried out in a suitable solvent, such as dichloromethane (CH2Cl2) or tetrahydrofuran (THF).
v. Major and minor end-products:
The major end-product of the hydrogenation reaction is the fully saturated alkane, resulting from the addition of hydrogen across the double bond. The minor end-product may include cis- or trans-configured alkanes if the original alkene substrate possesses geometric isomers.
vi. Intermediates:
The intermediates in the catalytic cycle include:
Rhodium dihydride complex: [RhH2(PPh3)3]Alkene-Rhodium π-complex: [Rh(η2-alkene)(PPh3)3]Metal-alkyl intermediate: [Rh(alkyl)(PPh3)3]These intermediates play a crucial role in facilitating the hydrogenation reaction and enabling the catalytic cycle to proceed.
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A 300.0 mL quantity of hydrogen is collected over water at 19.5 C and a total atmospheric pressure of 750. mm Hg. The partial pressure of water at this temperature is 17.0 mm Hg
Answers
The partial pressure of hydrogen in the collected gas sample is 733.0 mm Hg (calculated by subtracting the partial pressure of water, 17.0 mm Hg, from the total atmospheric pressure, 750.0 mm Hg).
When a gas is collected over water, the presence of water vapor affects the total pressure observed. In this case, the total atmospheric pressure is given as 750.0 mm Hg, and the partial pressure of water vapor at 19.5°C is 17.0 mm Hg.
To determine the partial pressure of hydrogen, we need to subtract the partial pressure of water vapor from the total atmospheric pressure. Partial pressure refers to the pressure exerted by an individual gas component in a mixture. In this scenario, the collected gas is primarily hydrogen, with water vapor being the other component.
By subtracting the partial pressure of water vapor (17.0 mm Hg) from the total atmospheric pressure (750.0 mm Hg), we can find the partial pressure of hydrogen:
Partial pressure of hydrogen = Total atmospheric pressure - Partial pressure of water vapor
Partial pressure of hydrogen = 750.0 mm Hg - 17.0 mm Hg
Partial pressure of hydrogen = 733.0 mm Hg
Therefore, the partial pressure of hydrogen in the collected gas sample is 733.0 mm Hg.
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. Calculate the number of moles in 5.00 × 102 g of each substance. How many molecules or formula units are present in each sample?
a. CaO (lime)
b. CaCO3(chalk)
c. C12H22O11 [sucrose (cane sugar)]
d. NaOCl (bleach)
e. CO2 (dry ice)
Answers
The number of moles in 500g of CaO, CaCO₃, C₁₂H₂₂O₁₁, NaOCl, and CO₂ are 8.93, 5, 1.46, 6.71 and 11.36 moles.
What is a mole?A mole is a scientific unit that is used to determine the number of atoms, molecules, ions, etc. The number of entities in 1 mole was found 6.023 × 10 ²³ per mole which is known as Avogadro’s constant.
a) Given, the mass of each substance = 5 ×10² g
The molar mass of CaO = 56 g
The number of moles in 5 ×10² g of CaO = 500/56 = 8.93 moles
The number of molecules in 8.90 moles of CaO = 8.93× 6.023 × 10 ²³
= 53.77 ×10²⁴ formula unit
b) The molar mass of CaCO₃ = 100 g
The number of moles in 5 ×10² g of CaCO₃ = 500/100 = 5 moles
The number of molecules in 5 moles of CaO = 5× 6.023 × 10 ²³
= 3.0 ×10²⁴ formula unit
c) The molar mass of C₁₂H₂₂O₁₁ = 342.3 g/mol
The number of moles in 5 ×10² g of C₁₂H₂₂O₁₁ = 500/342.3 = 1.46 moles
Number of molecules in 8.90 moles of C₁₂H₂₂O₁₁ = 1.46 × 6.023 × 10 ²³
= 8.8 × 10 ²³
d) The molar mass of NaOCl = 74.5 g/mol
The number of moles in 5 ×10² g of NaOCl = 500/74.5 = 6.71 moles
The number of molecules in 8.90 moles of CO₂ = 6.71× 6.023 × 10 ²³
= 4.04 ×10²⁴
e) The molar mass of CO₂ = 44 g/mol
The number of moles in 5 ×10² g of CO₂ = 500/44 = 11.36 moles
The number of molecules in 8.90 moles of CO₂ = 11.36× 6.023 × 10 ²³
= 6.84 ×10²⁴
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What is true about radioactive isotopes of an atom?
They are more abundant.
They are more stable.
They are less stable.
They are more scarce.
Answers
Answer: They are less stable
Explanation:
Answer:
The answer is C) They are less stable
Explanation:
Different isotopes of the same element have the same number of protons in their atomic nuclei but differing numbers of neutrons. Radioisotopes are radioactive isotopes of an element. They can also be defined as atoms that contain an unstable combination of neutrons and protons, or excess energy in their nucleus.
:)
The price of gold is $40.63/g. How many kg of gold would be worth $100?
Answers
Answer:
0.00246kg
Explanation:
1g = $40.63
$100 = $100/40.63 = 2.46g
2.46/1000 g = 0.00246kg
Direction: Write true if the statement is correct and false if it is in correct.
1. Gravity cause all objects to fall at the same rate of speed as there is no air
resistance.
Answers
True. 1.) Gravity cause all objects to fall at the same rate of speed as there is no air
resistance.
Explanation:In fact, gravity works independently of mass. This means that all objects should fall at the same rate.
If there is no air resistance, or the same amount of air resistance, then objects of the same mass will fall at the same rate.
#CarryOnLearningTrue or false Ocean currents drive Earth’s plates.
Answers
Answer:
False
Explanation:
Which of these space objects is the largest asteroid in the solar system?
Select one:
a. Pluto
b. Vesta
c. Ceres
d. Earth's Moon
Answers
Answer:
CERES is the latgest in the solar system
Explanation:
An isotope of hydrogen, known as Tritium (hydrogen-3), has a half-life of 12 years. If a sample of tritium was prepared 60 years ago, what was its original mass if its current mass is 0.42 micrograms?
Options for answers:
a.) 1.7mg b.) 13.4mg c.) 6.7mg d.) 26.8mg e.) 3.4mg
Answers
The original mass of Tritium (hydrogen-3) was 13.4mg if its current mass is 0.42 micrograms.
The formula for radioactive decay is given by:
N = N0 x (1/2)^(t/T)
where,
N = final number of radioactive atoms
N0 = initial number of radioactive atoms
t = time elapsed
T = half-life of the radioactive substance
Let's substitute the given values into the formula:
0.42 μg = N0 x (1/2)^(60/12)
0.42 μg = N0 x (1/2)^5
0.42 μg = N0 x 1/32
N0 = 0.42 μg x 32
N0 = 13.44 μg
Therefore, the original mass of the tritium sample was 13.44 micrograms.
What is radioactive decay?
Radioactive decay is the process by which an unstable atomic nucleus loses energy by emitting ionizing radiation, such as alpha particles, beta particles, and gamma rays. This process can result in a change in the number of protons and/or neutrons in the nucleus, leading to the transformation of one element into another. The rate of decay is typically characterized by a half-life, which is the time required for half of the atoms in a sample to decay.
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What is mass per unit volume called?
Answers
Answer:
The correct answer is Density
Explanation:
Hope this helps you
Answer:density
Explanation:
To assist with the self-administration of eye drops, you should refer to the manufacturer’s instructions because some eye drops need to be:
Answers
Before administering eye drops, make sure to wash your hands thoroughly with soap and water to minimize the risk of introducing any contaminants.
Tilting your head back or lying down can help create a better angle for administering the eye drops and prevent them from running out of your eye.
Use your index finger to gently pull down the lower eyelid, creating a small pocket.
Carefully hold the dropper tip close to your eye, without touching your eye or eyelashes.
Follow the specific instructions provided with your eye drops to determine the appropriate number of drops to use. Squeeze the dropper to release the drops into the pocket created by pulling down your lower eyelid.
If any excess solution has spilled onto your skin, gently wipe it away with a clean tissue or cloth to avoid irritation.
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Cryolite, Na3AlF6(s),
an ore used in the production of aluminum, can be synthesized using aluminum oxide.
equation:
Al2O3(s)+6NaOH(l)+12HF(g)⟶2Na3AlF6+9H2O(g)
If 10.3 kg of Al2O3(s),
55.4 kg of NaOH(l),
and 55.4 kg of HF(g)
react completely, how many kilograms of cryolite will be produced?
mass of cryolite produced:
Answers
The mass (in kilograms) of Cryolite, Na₃AlF₆ produced, given that 10.3 Kg of Al₂O₃, 55.4 Kg of NaOH, and 55.4 Kg of HF react completely is 42.4 Kg
How do i determine the mass of Na₃AlF₆ produced?The mass of Na₃AlF₆ produced from the reaction can be obtained as follow:
Al₂O₃(s) + 6NaOH(l) + 12HF(g) ⟶ 2Na₃AlF₆ + 9H₂O(g
Molar mass of Al₂O₃ = 102 g/molMass of Al₂O₃ from the balanced equation = 1 × 102 = 102 g = 102 / 1000 = 0.102 KgMolar mass of Na₃AlF₆ = 210 g/molMass of Fe from the balanced equation = 2 × 210 = 420 g = 420 / 1000 = 0.420 KgFrom the balanced equation above,
0.102 Kg of Al₂O₃ reacted to produce 0.420 Kg of Na₃AlF₆
Therefore,
10.3 Kg of Al₂O₃ will react to produce = (10.3 × 0.420) / 0.102 = 42.4 Kg of Na₃AlF₆
Thus, from the above calculation, it is evident that the mass of Na₃AlF₆ produced is 42.4 Kg
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2H2O = 2H2 +O2
If 30mL of hydrogen are produced in above reaction, how many mL of oxygen are produced? Please show work.
Answers
Answer:
15 mL of O₂.
Explanation:
The balanced equation for the reaction is given below:
2H₂O —> 2H₂ + O₂
From the balanced equation above,
2 mL of H₂O reacted to produce 2 mL of H₂ and 1 mL of O₂.
Next, we shall determine the volume of H₂O needed to produce 30 mL of H₂. This can be obtained as follow:
From the balanced equation above,
2 mL of H₂O reacted to produce 2 mL of H₂.
Therefore, 30 mL of H₂O will also react to produce 30 mL of H₂.
Thus, 30 mL of H₂O is needed for the reaction.
Finally, we shall determine the volume of O₂ produced from the reaction. This can be obtained as follow:
From the balanced equation above,
2 mL of H₂O reacted to produce 1 mL of O₂.
Therefore, 30 mL of H₂O will react to produce = (30 × 1)/2 = 30/2 = 15 mL of O₂.
Thus, 15 mL of O₂ were produced from the reaction.
Express in scientific notation 800678
Answers
Derive the van der Waals equation of state for a real gas and explain the significance of the law.
Answers
In the case of a real gas when you're using Van Der Waals equation, the volume of a real gas is considered as (Vm - b), where b can be considered as the volume occupied by per mole.
Therefore, when the ideal gas law gets substituted with V = Vm - b, it is given as : P(Vm - b) = nRT
The presence of intermolecular attraction P was modified as follows.
\(\frac{P+a}{V^{2} } (Vm- b) = RT\\\frac{P+an^{2} }{V^{2} } (V - nb) = nRT\)
Where, Vm: molar volume of the gas
R: universal gas constant
T: temperature
P: pressure
V: volume
Thus, it is possible to reduce Van Der Waals equation to the ideal gas law as PVm = RT.
What is the significance of the Ideal gas Law?
The ideal gas law only functions as an approximation approach when high accuracy is not necessary because it describes the behaviour of ideal gasses, which there aren't any of. It is a solid introduction to the fundamental behaviour of gases and works well as a teaching tool, which is why it is taught to the majority of university students as part of any introduction to physics. In essence, the ideal gas law enables students to comprehend ideas such as the process of thermodynamic cycles, such as an engine, the reason an airbag expands, what transpires to a balloon at high altitude, and other related ideas.
Hence, Van Der Waals equation to the ideal gas law as PVm = RT.
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Based on the synthesis reaction, what would the product of the reaction be? NaPO3 + CuO → ? NaO + CuPO3 Na + P + Cu + O4 NaCuPO4 NaCu + PO4
Answers
Answer:
C
Explanation:
Based on the synthesis reaction,the product of the given chemical equation is NaCuPO4 .
What is chemical equation?Chemical equation is a symbolic representation of a chemical reaction which is written in the form of symbols and chemical formulas.The reactants are present on the left hand side while the products are present on the right hand side.
A plus sign is present between reactants and products if they are more than one in any case and an arrow is present pointing towards the product side which indicates the direction of the reaction .There are coefficients present next to the chemical symbols and formulas .
The first chemical equation was put forth by Jean Beguin in 1615.By making use of chemical equations the direction of reaction ,state of reactants and products can be stated. In the chemical equations even the temperature to be maintained and catalyst can be mentioned.
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What is the wavelength of the yellow sodium emission, which has a frequency of 5.09 x 10^14/s?
Answers
Answer:
5.89×10^-7 meters
Explanation:
wavelength= speed of light/frequency
3.00×10^8m/s÷5.09×10^14s=5.89×10^-7 meters
How do particles tend to move in solids?
They vibrate about fixed points.
They move randomly through the solid while remaining in close contact with other particles.
They move in orbits around a center.
They move randomly through the solid and separately from other particles.
Answers
Which statement about pure substances and molecules is correct?
O All pure substances are molecules.
O All molecules are pure substances.
o Molecules cannot be pure substances.
O Pure substances cannot be molecules.
Answers
A molecule must be a pure substance hence the correct answer is " All molecules are pure substances."
A pure substance is one which contains only one element or compound. A molecule is the smallest unit of a compound that can exist independently.
When we refer to a molecule of a compound, we are referring to that pure substance that contains only the element(s) that compose the compound.
Hence; All molecules are pure substances.
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g) How many grams of aluminum (Al) are present in 2.98 mol of Al?
h) How many moles of Br are there if the sample contained 5.6 x 1024 atoms of Br?
Answers
Answer:
26.982 g
i think so..........
You have 100. grams of potassium bromide (KBr). How many moles do you have? (1 mole KBr = 119 g KBr)
0.840 mole KBr
1.00 mole KBr
1.19 mole KBr
2.00 mole KBr
Answers
Answer:
0.840
Explanation:
The 100 grams of KBr have been equivalent to 0.84 moles. Thus, option A is correct.
The moles can be defined as the mass of the compound with respect to the molecular mass. The moles can be given as:
Moles = \(\rm \dfrac{weight}{Molecular\;weight}\)
The molecular weight has been the mass of the constituents of the atoms present in the compound.
The compound KBr has a molecular mass of 119 g/mol.
The given mass of the compound has been 100 grams.
The moles of KBr can be given as:
Moles of KBr = \(\rm \dfrac{100}{119}\)
Moles of KBr = 0.84 moles.
The 100 grams of KBr have been equivalent to 0.84 moles. Thus, option A is correct.
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Which is not a physical property? ability to combine with oxygen boiling point ability to conduct electricity hardness
Answers
Answer:
A
Explanation:
The ability to combine with oxygen is not a physical property it is a physical change i believe.
boiling point is a property as well as conducting electricity and hardness
For measurement of volume which glassware you will use?
A
Graduated cylinder
B
Beaker
C
Balance
D
Erlenmeyer
Answers
The chart shows the frequencies of certain colors of visible light. A 2 column table with 4 rows. The first column is labeled light with entries red, violet, green, orange. The second column is labeled frequency in hertz with entries 4.5 times 10 Superscript 14 baseline, 7.5 times 10 Superscript 14 baseline, 6.0 times 10 Superscript 14 baseline, 5.0 times 10 Superscript 14 baseline. Which colors will eject electrons when they strike sodium, which has a frequency threshold of 5.7 × 1014 Hz? violet and green red and orange violet only red, violet, green, and orange
Answers
Answer:
Violet only
Explination:
Violet is the only color that will eject electrons when it strikes sodium.
The colors that will eject electrons when there's a strike with sodium from the chart will be A. Violet and green.
ElectronsFrom the complete information, William made a chart in order to illustrate the result of the experiment that was made with the photoelectric effect.
In this case, the colors that will eject electrons when they strike sodium, with the frequency threshold will be violet and green.
This was gotten from the result that the frequencies of light were lower than the frequency threshold.
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