what causes the outer layer of star to expand?
Answer/Explanation:
Stars spend the majority of their lifespan medling hydrogen nuclei together to form helium. When the hydrogen that in the core of the star begins to run out, the star will start using hydrogen away from its core and this is what causes the star's outer layer to expand and slowly cool down.
I hope this helps!
-No one
Hello people ~
Friction always
(a) opposes the motion
(b) helps the motion
(c) both (a) and (b)
(d) none of these
Answer:
Opposes the motion
Explanation:
Let's take an example
Suppose you kicked a ball and the ball is doing down the groundThe friction makes the ball to stop after sometime .So it opposed the ball's motionoption A is correct
if there are 0.0023 moles of water in a sample, how many molecules are there?
39 g H
2
O
contains
1.3
×
10
24
molecules H
2
O
.
Explanation:
One mole of water has a molar mass of
18.015 g/mol
and
6.022
×
10
23
molecules H
2
O
. Therefore,
1 mol H
2
O
=
18.015 g H
2
O
=
6.022
×
10
23
molecules H
2
1O
Multiply the given mass of water times the conversion factors that cancel grams and moles of water, leaving molecules of water, as demonstrated below.
39
g H
2
O
×
1
mol H
2
O
18.015
g H
2
O
×
6.022
×
10
23
molecules H
2
O
1
mol H
2
O
=
1.3
×
10
24
molecules H
2
O
39 g H
2
O
contains
1.3
×
10
24
molecules H
2
O
.
Explanation:
One mole of water has a molar mass of
18.015 g/mol
and
6.022
×
10
23
molecules H
2
O
. Therefore,
1 mol H
2
O
=
18.015 g H
2
O
=
6.022
×
10
23
molecules H
2
1O
Multiply the given mass of water times the conversion factors that cancel grams and moles of water, leaving molecules of water, as demonstrated below.
39
g H
2
O
×
1
mol H
2
O
18.015
g H
2
O
×
6.022
×
10
23
molecules H
2
O
1
mol H
2
O
=
1.3
×
10
24
molecules H
2
O
39 g H
2
O
contains
1.3
×
10
24
molecules H
2
O
.
Explanation:
One mole of water has a molar mass of
18.015 g/mol
and
6.022
×
10
23
molecules H
2
O
. Therefore,
1 mol H
2
O
=
18.015 g H
2
O
=
6.022
×
10
23
molecules H
2
1O
Multiply the given mass of water times the conversion factors that cancel grams and moles of water, leaving molecules of water, as demonstrated below.
39
g H
2
O
×
1
mol H
2
O
18.015
g H
2
O
×
6.022
×
10
23
molecules H
2
O
1
mol H
2
O
=
1.3
×
10
24
molecules H
2
O
Given the reaction: 2Na + 2H2O --> 2NaOH + H2 How many moles of Na are needed to produce exactly 5.6 liters of H2, measured at STP?
For a reaction 2Na + 2H2O --> 2NaOH + H2, The moles of Na needed to produce exactly 5.6 liters of H2 is mathematically given as
moles of H2=0.125mole
How many moles of Na are needed to produce exactly 5.6 liters of H2,?
Generally, the equation for the Chemical Reaction is mathematically given as
2Na + 2H2O -> 2NaOH + H2(g)
Therefore, since 2Na gives 1H2
PV=nRT
Hence
n=PV/RT
n=1*5.6/0.0821 *273
n=0.249mols
In conclusion,The moles is
2Na=1H2
moles of H2=0.125mole
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What does an electromagnetic spectrum refer to?
A gas has a mass of 3.82 g and occupies a volume of 0.854 L. The temperature in the laboratory is 302 K, and the air pressure is 1.04 atm. calculate the molar mass of the gas.
1) 93.4 g/ mol
2) 72.3 g/ mol
3) 107 g/ mol
4) 35.8 g/mol
The molar mass of the gas that has a mass of 3.82 g and occupies a volume of 0.854 L is 106.66g/mol.
How to calculate molar mass?The molar mass of a substance can be calculated by dividing the mass of the substance by its number of moles.
However, the number of moles of the gas in this question needs to be calculated first using the ideal gas law equation:
PV = nRT
Where;
P = pressureV = volumen = number of molesT = temperatureR = gas law constant1.04 × 0.854 = n × 0.0821 × 302
0.888 = 24.79n
n = 0.888/24.79
n = 0.036mol
Molar mass of gas = 3.82g/0.036mol
Molar mass = 106.66g/mol
Therefore, the molar mass of the gas that has a mass of 3.82 g and occupies a volume of 0.854 L is 106.66g/mol.
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A quantity of helium gas occupies 5 liters at room temperature and standard atmospheric
pressure (760 mm Hg). If the temperature stays the same, what will be the volume o
the helium if the pressure is increased to 950 mm of mercury?
The new volume of occupied by helium gas when its pressure is increased from 760 mm Hg to 950 mm Hg at an initial volume of 5 L is equal to 4 L.
Boyle's LawBoyle's law state that at constant temperature, the volume of a fixed mass of gas is directly proportional to its pressure.
To calculate the volume of the helium gas, we use the formula below.
Formula:
P₁V₁ = P₂V₂............. Equation 1
Where:
P₁ = Initial pressureV₁ = Initial volumeP₂ = Final pressureV₂ = Final volume.Make V₂ The subject of the equation
V₂ = P₁V₁/P₂............... Equation 2From the question,
Given:
P₁ = 760 mm HgV₁ = 5 LP₂ = 950 mm HgSubstitute these values into equation 2
V₂ = (760×5)/950V₂ = 4 L.Hence, The new volume of occupied by helium gas when its pressure is increased from 760 mm Hg to 950 mm Hg at an initial volume of 5 L is equal to 4 L.
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What is density? (1 point) the amount of space occupied by a substance or body O the quantity of matter contained in a substance or body o the amount of heat contained in a body o the degree of compactness of a substance
Answer:
density answer IS ....
The main purpose of homeostasis is to
A. fight disease-causing organisms.
B. keep internal conditions stable.
C. produce offspring.
D. replicate DNA.
Methane from ohio's rose valley coal mine has successfully been used to power fuel cells. since the fuel used in these cells is not burned, using methane from this mine will help to
a.increase public awareness of global warming issues
b.increase the concentration of atmospheric ozone
c.reduce public demand for alternative fuel souces
d.reduce pollutants commonly associated with fossil fuel combustion
Methane in fuel cells are not burned and therefore, help to reduce pollutants commonly associated with fossil fuel combustion.
What are fossil fuels?Fossils fuels are fuels wgich are produced from fossils which have decomposed under intense heat and pressure over a long period of time.
Fossils fuels include:
methanepetrolkerosenediesel oilcoalFossils fuels combustion release pollutants into the atmosphere and have greatly contributed to global warming.
Since methane in fuel cells are not burned, it will help to reduce pollutants commonly associated with fossil fuel combustion.
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Which statement best describes the law of conservation of mass? (1 point)
O Chemical symbols are used to show atom balance before and after a reaction.
O Matter cannot be created or destroyed in a chemical reaction.
O Reactants and products cannot escape from a closed system
• Reactants in a chemical reaction rearrange to form a new substance or substances.
Matter cannot be created or destroyed in a chemical reaction best describe law of conservation of mass.
What is law of conservation of mass?The law of conservation of mass states that for any system closed Mass can neither be created not destroy. the mass of the system must remain constant over time,.
Therefore, Matter cannot be created or destroyed in a chemical reaction best describe law of conservation of mass.
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I have my last 3 electrons on the third energy level.
Answer:
an energy level represents the three dimensional space surrounding nucleus where electrons are most likely to be.
Explanation:
What is the energy required to remove the electron from a hydrogen atom in the n = 11 state?
Based on the data given, the energy required to remove an electron from a hydrogen atom in the n = 11 state is -0.112 eV
What is ionization energy?Ionization energy is the energy requiredto remove an electron from a neutral atom or a cation in its gaseous state.
To calculate the energy required to remove the electron from a hydrogen atom in the n = 11 state, the formula below is used:
[tex]E_n = \frac{E_0 × Z^{2}}{n^{2}}[/tex]where
[tex]E_0 \: is \: ground \: state \: energy \: of \: hydrogen \: atom \: = -13.6 eV \\ [/tex]
Z = 1n = 11substituting the values:
[tex]E_n = \frac{ - 13.6 × 1^{2}}{11^{2}} \: = - 0.112 \: eV[/tex]
Therefore, the energy required to remove an electron from a hydrogen atom in the n = 11 state is -0.112 eV
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Compare the relative strength of the two forces A and B. Explain how you determined this comparison by identifying the forces.
The intermolecular forces present in B will be much stronger than the intermolecular forces present in A.
What are intermolecular forces?The term intermolecular forces has to do with the forces that hold molecules of a substance together in a particular state of matter. Now, we can see that B must contain dipole - dipole interaction while A has none of these.
It then follows that the intermolecular forces present in B will be much stronger than the intermolecular forces present in A.
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find the oxidation state of c in (NH4)2 CO3
Answer:
Ammonium carbonate is a neutral molecule. Charge on NH4 is +1 , so on (NH4)2 is +2 ( +1 * 2) ,lets take the charge on C to be x and O is -2 , so on O3 is -6 (3*-2). Therefore x= + 4. Hope it helps.
Explanation:
How would you describe the temperature of an object that has very slow moving particles?
The chemical equation below shows the photosynthesis reaction. 6co2 6h2o right arrow. c6h12o6 6o2 the molar mass of carbon dioxide (co2) is 44.01 g/mol. the molar mass of water (h2o) is 18.02 g/mol. a reaction uses 528 g of co2. how many moles of water are used in this reaction? 12.0 moles 72.0 moles 216 moles 528 moles
The moles of water are used in the given reaction between CO₂ & H₂O is 12 moles.
How do we calculate mass from moles?Mass of any substance will be calculated by using their moles as:
n = W/M , where
W = given or required mass
M = molar mass
Given chemical reaction is:
6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂
Moles of 528 g of CO₂ = 528g / 44.01g/mol = 11.99 moles
From the stoichiometry of the reaction, it is clear that:
6 moles of CO₂ = reacts with 6 moles of H₂O
So, 11.99 moles of CO₂ = reacts with 11.99 = 12 moles of H₂O
Hence option (a)is correct i.e. 12 moles.
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Answer:
A
Explanation:
In healthcare settings where sterilization is an absolute necessity, what method of sterilization will typically be used?
pasteurizing
disinfecting
autoclaving
boiling
lyophilizing
Answer:
Disinfecting (or boiling)
Explanation:
They'd want to disinfect everything so that it is germless. Boiling is a possible answer as well because you can boil certain things to rid them of germs.
Determine the product(s) formed when cyclohexene is treated with the following reagents
Explanation:
Big C carbon surrounded by He helium
hello people ~
Identify the type of plastic that can best be used to make electrical switches.
A. PVC
B. Polythene
C. PET
D. Bakelite
Answer:
Bakelite
Explanation:
Bakelite is a non recyclable plasticSimilar to Melamine it has some of very bad heat and electricity conducter.So it's used in electrical switchesDuring an experiment, ice and water were placed in a perfectly insulated thermos flask at 0 °C. Describe this system when it phase reaches equilibrium. (8 points)
Answer :By the time thermal equilibrium is attained in the system, ice is completely converted to water.
What is tehrmal equilibrium?
Thermal equilibrium is a situation in which two substances are exactly at the same temperature. That is. Heat is no longer flowing beween the bodies.
Recall that an insulated thermos flask implies that heat does not eneter or leave the system. Heat will flow from the water to the ice untill the both attains the same temperature and the ice is completely converted to water.
Have a good day
i need help from the problem below
Answer:
I won't say I'm confident with this because I'm not sure if the second one is even correct, but I hope I helped you and didn't make things worse lol.
What type of material does not allow electrons to flow easily?
neutral particles since they do not posses any charge
Which of the following shows the proper configuration for the straight chain isomer of butane?
Answer:
option C is the correct answer
Explanation:
it belongs to alkanes series
for alkane series the formula is
C n H 2n+2
so the formula of b utane is
C 4 H 10
The correct answer is option C.C4H10
What is straight chain isomerism?
These isomers occur because they can branch off at the carbon chain. For example, butane has two isomers, C4H10. One of them has a "linear" carbon atom and the other has a branched chain.
Butane is a 4-carbon alkane, so its molecular formula is C4H10. There are two isomers. n-Butane and isobutane. Here, n-butane is a linear compound with four carbon atoms connected by a single covalent bond.
\Compounds with the same molecular formula but different arrangements of carbon atoms in the straight or branched chain are called chain isomers. n-Butane and isobutane are chain isomers because they have different carbon atom arrangements
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If a buffer is composed of 33. 80 ml of 0. 164 m acetic acid and 31. 63 ml of 0. 189 m sodium acetate, how many ml of 0. 100 m hcl can be added before the buffer capacity is reached?
For a buffer is composed of 33. 80 ml of 0. 164 m acetic acid and 31. 63 ml of 0. 189 m sodium acetate,The volume of HCl is mathematically given as
v1=70.1148mL
What volume of HCL can be added before the buffer capacity is reached?Generally, the equation for the Chemical reaction is mathematically given as
HCl+CH3Coo-Na---->CH3CooH+NaCl
Therefore
Mole of HCl=34.37*0.204*10^-3
Mole of HCl=7.011*10^-{-3}
In conclusion
M1v1=m2v2
Therefore
[tex]v1=\frac{m2v2}{m1}\\\\v1=\frac{7.011*10^-{-3}}{0.1}[/tex]
v1=70.1148mL
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70.114 ml of 0. 100 m HCl can be added before the buffer capacity is reached
What is volume?Volume is the space occupied by a three-dimensional object.
The chemical reaction is
[tex]\rm HCl+CH_3Coo-Na---- > CH_3CooH+NaCl[/tex]
step1, calculate the moles of HCl
[tex]34.37 \times0.204\times 10^-3[/tex]
[tex]\rm Moles\; of\; HCL \;7.011\times 10^{-3}[/tex]
The given Volume 1 is 33.80 ml
The given volume 2 is 31.63 ml
By the formula, [tex]M_1V_1=M_2V_2[/tex]
Putting the values in the equation
[tex]0.164 \times 33.80 = 100 \times V_2\\\\V_2 = 70.114 ml.[/tex]
Thus, the final volume is 70.114 ml.
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v1=70.1148mL
What units are appropriate to express specific heat?.
Answer:
joules per gram per degree (J/goC) or calories per gram per degree (cal/goC).
Explanation:
Answer:
Joules, Kelvin, or calories
Explanation:
The picture above shows a frying pan. Why are frying pans usually made out of metal?
Answer: The frying pan is made up of metals like aluminium or stainless steel as these metals are good conductor of heat.
Answer:
b. they are good conductors of heat
Explanation:
study island
2) Usually, when the particle size is decreased, what will happen to the rate of dissoving?
A) It will stop.
B) It will increase.
C) It will decrease.
D) It will remain constant.
How much hcl must be added to a liter of buffer that is 1. 5 m in acetic acid and 0. 70 m in sodium acetate to result in a buffer ph of 4. 01?]
For a liter of a buffer that is 1. 5 m in acetic acid and 0. 70 m in sodium acetate, and with a result in a buffer pH of 4.01, the moles of HCl required is mathematically given as x=0.313mol
What is the result in a buffer ph of 4. 01?Generally, the equation for the pH is mathematically given as
pH=pKa+logsalt/acid
Generally, the equation for the Chemical Reaction is mathematically given as
HCl+CH3CooNa---->NaCl+CH3OOH
Therefore
4.01=4.74+log\frac{0.8-x}{1.3+x}
-0.52=log\frac{0.8-x}{1.3+x}
x=0.313mol
In conclusion, The moles of HCl required is
x=0.313mol
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Buffer is a solution that prevents pH variation in a solution when base or acid is added. In a liter of buffer 0.313 mol of hydrochloric acid must be added.
What is pH?pH is the potential of hydrogen and is given as,
[tex]\rm pH =\rm pKa + log \dfrac{salt}{acid}[/tex]
The chemical reaction is given as,
[tex]\rm HCl+CH_{3}COONa \rightarrow NaCl+CH_{3}OOH[/tex]
Given,
pH =4.01
pKa = 4.74
Concentration of salt = 0.8 - x
Concentration of acid = 1.3 + x
Substituting values in the pH formula:
[tex]\begin{aligned} 4.01 &= 4.74 + \rm log \dfrac{(0.8 - x)}{ (1.3 + x)}\\\\-0.52 &= \rm log \dfrac{(0.8 - x)}{ (1.3 + x)}\\\\&= 0.313 \;\rm mol\end{aligned}[/tex]
Therefore, 0.313 moles of HCl are needed.
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Do you think that parents should be able to design their babies using gene technology such as CRISPR?
Make sure you have 4 or 5 sentences for your answer.
Answer:
When Chinese researchers first edited the genes of a human embryo in a lab dish in 2015, it sparked global outcry and pleas from scientists not to make a baby using the technology, at least for the present.
When Chinese researchers first edited the genes of a human embryo in a lab dish in 2015, it sparked global outcry and pleas from scientists not to make a baby using the technology, at least for the present.It was the invention of a powerful gene-editing tool, CRISPR, which is cheap and easy to deploy, that made the birth of humans genetically modified in an in vitro fertilization (IVF) center a theoretical possibility
Explanation:
Now, it appears it may already be happening.
According to Chinese medical documents posted online this month (here and here), a team at the Southern University of Science and Technology, in Shenzhen, has been recruiting couples in an effort to create the first gene-edited babies. They planned to eliminate a gene called CCR5 in hopes of rendering the offspring resistant to HIV, smallpox, and cholera.