c option is correct answer
When did China's earliest civilization originate?
Answer:
The Chinese civilization really has an exact chronology, and the historical period began in the first year of the Western Zhou Dynasty in 841 BC. Before that, only the lineage records of the kings were recorded. Therefore, the earliest origin of Chinese civilization has not yet been finalized. Although there are many records about the Xia Dynasty in the traditional literature, due to the late completion of the book, there is no recognized evidence of the existence of the Xia Dynasty and its previous history. Therefore, some people in the modern and modern historical circles have always questioned the existence of the Xia Dynasty. sex.
Explanation:
What is the osmotic pressure, in atm, of a 0.287 M solution of MgCl2 at
37.0 °C? (assume complete dissociation).
Answer:
Π = 21.9 atm
Explanation:
The equation used to find osmotic pressure is:
Π = iMRT
In this formula,
>> Π = osmotic pressure (atm)
>> i = van't Hoff factor
>> M = molarity (M)
>> R = constant (0.0821 atm*L/mol*K)
>> T = temperature (K)
Remember, van't Hoff factor is the amount of ions the species (MgCl₂) dissociates into while in solution. MgCl₂ dissociates into 3 ions. These ions are Mg²⁺ and 2 Cl⁻.
The temperature needs to be in Kelvin....
37.0 °C + 273.15 = 310.15 K
You now know the value of all the variables.
Π = iMRT
Π = (3)(0.287 M)(0.0821 atm*L/mol*K)(310.15 K)
Π = 21.9 atm
Determine the hybrid orbital of this molecule.
There are three sigma bonds, so hybridization of the molecule will be sp²
A temperature of 300 Kelvin is how many degrees Celsius?
A. 273
B. 27
C. 573
D. 300
Answer:
The answer is B, to convert kelvin to temperature you :
Subtract 273 (k - 273)
What hazard symbol does Pesticides have?
The hazard symbol that pesticides have are skull and cross bones.
What are hazard symbols?Hazard symbols represent those symbols that are used as a warning sign towards materials that are dangerous to health.
Example of symbols used are:
Exploding bomb symbol: used for explosivesFlame symbol: used for flammablesskull with cross bones symbol: used for toxic substances such as pesticides.Therefore, the hazard symbol that pesticides have are skull and cross bones.
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The hazard symbol of pesticides is a picture of the skull and crossbones.
What are pesticides?Pesticides are known as substances that are meant to control or destroy pests. They include herbicide, insecticide, nematicide, avicide, rodenticide, bactericide, insect repellent, etc.
The hazard symbol of pesticides is a picture of the skull and crossbones
Thus, the hazard symbol of pesticides is a picture of the skull and crossbones.
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Explain why the compound Cl2O has a low melting and boiling point.
Write and balance the equation for the combustion of the fatty acid lauric acid, (C12H24O2).
C12H24O2 +17 O2-------->12CO2 + 12H2O
Combustion:-
combustion is a chemical reaction that often involves the presence of oxygen and produces heat and light in the form of flames.
Lauric acid:-Lauric acid has a 12-carbon backbone and is a saturated medium-chain fatty acid. In addition to being a key component of coconut oil and palm kernel oil, lauric acid occurs naturally in a variety of plant and animal fats and oils.
White solid lauric acid has a little bay oil odour to it.
Lauric acid is a cheap, non-toxic, and easy-to-handle substance that is frequently employed in lab studies on melting-point depression. Because lauric acid is a solid at ambient temperature but a liquid at boiling temperatures, it can be used to test different solutes to determine their molecular weights.
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Refer to the following table of Ksp values to answer the question below.
Compound
PbS
SnS
ZnS
HgS
Ksp
3 x 10-29
1 x 10-26
2x 10-25
1.6 x 10-52
A solution has 0.01 M Pb²+, 0.01 M Sn²+, 0.01 M Zn²+, and 0.01 M Hg2+. As tiny amounts of sulfide ion are slowly added
to the solution, which compound will precipitate first?
PbS
O Fes
HgS
SnS
HgS will precipitate first when tiny amounts of sulfide ion are slowly added to the solution.
What is Ksp?The solubility product constant, Ksp, is the equilibrium constant for a solid substance dissolving in an aqueous solution. It represents the level at which a solute dissolves in solution.
If Solubility product is greater than the ionic product then no precipitate will form on adding more solute because unsaturated solution is formed.
If Solubility product is lower than the ionic product then excess solute will precipitate out because of the formation of super saturated solution.
Here, Ksp value of HgS is very low. Hence, HgS will precipitate first when tiny amounts of sulfide ion are slowly added to the solution.
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How many significant figures does 7,874.9640 s have?
Submit Question
Answer:
8 significant figures
Explanation:
All numbers (that are not zero) are always significant. Because there is a zero at the end of the number after the decimal place, this makes this zero also significant. This zero is significant because it makes the number more precise. Therefore, all of the numbers in this number are significant.
Answer:
There are 8 sig figs
Explanation:
The equilibrium constant for the reaction 2 C3H6(g) ↔ C2H4(g) + C4H8(g) Is found to fit the expression: lnK = A + B/T + C/T2, between 300 and 600 K, where A = -1.04, B = -1088 K, C = 1.51x105 K2. Calculate the standard reaction enthalpy and standard reaction entropy at 400 K.
The standard reaction enthalpy and the standard reaction enthalpy at 400 K for this reaction are equal to 0.35 kJ and 0.000125 kJ respectively.
How to calculate Gibbs's free energy?Mathematically, the Gibbs's free energy for this chemical reaction can be calculated by using this formula:
ΔG° = -RTlnK = ΔH° - TΔS° ......equation 1.
First of all, we would determine the value of lnK from the given expression at 390 K and 410 K respectively:
lnK = A + B/T + C/T²
lnK = -1.04 - 1088/T + 1.51 × 10⁵/T²
lnK = -1.04 - 1088/390 + 1.51 × 10⁵/390²
lnK = -1.04 - 2.79 + 0.99
lnK = -2.84.
At T = 410 K, we have:
lnK' = -1.04 - 1088/410 + 1.51 × 10⁵/410²
lnK' = -1.04 - 2.65 + 0.90
lnK' = -2.79.
For the standard reaction enthalpy, we have:
lnK' - lnK = ΔH°/R(1/T - 1/T')
-2.79 - (-2.84) = ΔH°/8.314(1/390 - 1/410)
-2.79 + 2.84 = ΔH°/8.314(0.00256 - 0.00244)
0.05 = ΔH°/8.314(0.0012)
0.4157 = 0.0012ΔH°
ΔH° = 0.4157/0.0012
ΔH° = 346.42 ≈ 0.35 kJ.
Next, we would determine the Gibbs's free energy at each temperature:
At T = 390 K, we have:
ΔG° = -RTlnK
Δ₁G° = -8.314 × 390 × (-2.84)
Δ₁G° = 9.21 kJ/mol.
At T = 410 K, we have:
Δ₂G° = -8.314 × 410 × 2.79
Δ₂G° = 9.51 kJ/mol.
For the standard reaction enthalpy at 400 K, we have:
ΔG° = ΔH° - TΔS°
9.51 - 9.21 = 0.35 - 400ΔS°
0.30 = 0.35 - 400ΔS°
400ΔS° = 0.35 - 0.30
400ΔS° = 0.05
ΔS° = 0.05/400
ΔS° = 0.000125 kJ.
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An unknown gas effuses at a rate of 2.0 times the rate of Cl₂. What is the molar mass of the unknown gas?
The molar mass of the unknown gas is determined as 17.75 g.
Rate of gas diffusionThe rate of gas diffusion is given by Graham's law.
R₁√M₁ = R₂√M₂
where;
R₁ is the rate of diffusion of the unknown gasM₁ is the molecular mass of the unknown gasR₂ is rate of diffusion of chlorine gasM₂ is the molecular mass of chlorine gas[tex]\frac{R_1}{R_2} = \sqrt{\frac{M_2}{M_1} } \\\\\frac{2R_2}{R_2} = \sqrt{\frac{71}{M_1} }\\\\2 = \sqrt{\frac{71}{M_1} }\\\\2^2 = \frac{71}{M_1} \\\\M_1 = \frac{71}{4} \\\\M_1 = 17.75 \ g[/tex]
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What is open system?
What is close system?
What is the valency of an atom?
State Heisenberg uncertainty principle
Define endothermic reaction
Answer:
1) open system is the system through which both matter and energy and enter as well as leave
ex - open beaker
2) close system is the system through which only energy can leave but matter cannot
ex - pressure cooker.. ( energy leave as air)
3) Valency of an atom is the no. of outer most electron which can participate in a reaction.
4). Heisenberg uncertainty principal states that it is impossible to measure or calculate exactly, both the position and the momentum of an object
5) The reaction in which heat is required to make products are called endothermic reaction. it cools down the surrounding .
How many molecules in HNO3?
In an experiment, a student gently heated a hydrated copper compound to remove the water of hydration. The following data was recorded:
Mass of crucible, cover, and contents before heating = 23.4 g.
Mass of empty crucible and cover = 18.82 g.
Mass of crucible, cover, and contents after heating to constant mass = 20.94 g.
The percent of water in the hydrated salt will be 55.08 %
What is mass?Mass is a numerical measure of quantity, which is a basic feature of all matter. The kilogram is the international system of units of mass.
Given data;
Mass of crucible, cover, and contents before heating = 23.4 g.
Mass of empty crucible and cover = 18.82 g.
Mass of crucible, cover, and contents after heating to constant mass = 20.94 g.
⇒Mass of hydrated salt used = Mass of the crucible, cover, and contents before heating - Mass of the empty crucible and cover
⇒Mass of hydrated salt used = = 23.54 g – 18.82 g
⇒Mass of hydrated salt used = = 4.72 g
⇒Mass of dehydrated salt after heating = Mass of the crucible, cover, and contents after heating to constant mass-Mass of the empty crucible and cover
⇒Mass of dehydrated salt after heating = 20.94 g – 18.82 g
⇒Mass of dehydrated salt after heating = 2.12 g
⇒ Mass of water liberated from salt = Mass of hydrated salt used - Mass of dehydrated salt after heating
⇒ Mass of water liberated from salt = 4.72 g – 2.12 g
⇒ Mass of water liberated from salt = 2.60 g
Water % in the hydrated salt is found as;
% water =(mass of water/ mass of hydrated salt)× 100
% water =(2.60/4.72) × 100
% water =55.08 %
Hence the percent of water in the hydrated salt will be 55.08 %
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Determine the hybrid orbital of this molecule.
The hybrid orbital of this molecule is [tex]sp^3[/tex]. Hence, option C is correct.
What is hybridisation?Hybridization is defined as the concept of mixing two atomic orbitals to give rise to a new type of hybridized orbitals.
In this compound, [tex]sp^3[/tex] a hybrid orbital makes I-O bonds. Due to [tex]sp^3[/tex]hybridization iodate should have tetrahedral geometry but because of the presence of lone pair of electrons the shape of [tex]IO^{3-}[/tex] the ion is pyramidal.
The hybrid orbital of this molecule is [tex]sp^3[/tex]. Hence, option C is correct.
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Balanced chemical equation: BaCl2(aq)+Na2SO4(aq)⟶BaSO4(s)+2NaCl(aq)
Using 1.46 moles of NaCl, determine how many grams of NaCl can be produced.
Then, using the moles of NaCl found in a previous question, determine how many formula units of NaCl can be produced. formula units:
Answer:
Part 1) 85.3 grams NaCl
Part 2) 8.79 x 10²³ formula units NaCl
Explanation:
(Part 1)
To find the mass of NaCl, you need to multiply the given value (1.46 moles) by the molar mass of NaCl. This measurement is the atomic masses of the elements times each of their quantities combined. In this case, there is only one mole of each element in the molecule. Moles should be located in the denominator of the conversion to allow for the cancellation of units. The final answer should have 3 sig figs to reflect the given value.
Molar Mass (NaCl): 22.99 g/mol + 35.45 g/mol
Molar Mass (NaCl): 58.44 g/mol
1.46 moles NaCl 58.44 g
--------------------------- x ---------------- = 85.3 grams NaCl
1 mole
(Part 2)
I do not know which other question the second part is referring to, so I will just use the moles given in the first part. To find the formula units, you need to multiply the given value (1.46 moles NaCl) by Avogadro's Number. This conversion represents the number of formula units found in 1 mole of the sample. The moles should be in the denominator of the conversion to allow for the cancellation of units.
Avogadro's Number:
1 mole = 6.022 x 10²³ formula units
1.46 moles NaCl 6.022 x 10²³ units
------------------------ x ----------------------------- = 8.79 x 10²³ formula units NaCl
1 mole
Describe the subatomic structure of the nucleus, including the structure of each nucleon. Draw a picture. Describe the forces that hold the nucleus together and draw them on your diagram. Explain how beta emission works.
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Three students are given a 200g object to weigh on a balance and record the following masses: 150g, 151g 150g. What can be said about the accuracy and precision of the balance?
In a container with 512.1 L water, the pH should be changed to 5 using 95% sulfuric acid. The question is how much sulfuric acid is needed.
Answer:
15
Explanation:
I got it right I just had the answer
What is the frequency of the green light emitted by a hydrogen atom with a wavelength of 525 nm?
The frequency of the green light emitted by a hydrogen atom with a wavelength of 525 nm is [tex]5.71[/tex]×[tex]10^{14} s^{-1}[/tex]
What is wavelength?
It is the length between two successive crests or troughs of any wave.What is a frequency?
It is the total number of waves that pass through a fixed point in unit time.Wavelength=525nm
The relation between wavelength and frequency
[tex]v=\frac{c}{lambda}[/tex]
[tex]v=[/tex]frequency
[tex]c=[/tex]speed of light = [tex]3.0[/tex]×[tex]10^{8}[/tex][tex]m/sec[/tex]
λ(lambda)=wavelength
substitute the value in the equation mentioned above
[tex]v=3.0[/tex]×[tex]10^{8}[/tex][tex]/525[/tex]×[tex]10^{-9}[/tex]
[tex]=5.71[/tex]×[tex]10^{14}[/tex][tex]s^{-1}[/tex]
hence, the frequency of the green light emitted by a hydrogen atom with a wavelength of 525 nm is [tex]5.71[/tex]×[tex]10^{14} s^{-1}[/tex]
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uses of radio isotopes
Answer:
1. Used in many smoke detectors for homes and businesses to measure levels of toxic lead in dried paint sample to ensure uniform thickness in rolling processes like steel and paper production and to help determine where oil wells should be drilled.
2.Used to treat cancerous tumors to measure correct patient dosages of radioactive pharmaceutical to measure and control the liquid flow in oil pipelines to tell researchers whether oil wells are plugged by sand and to ensure the right fill level for packages of food, drugs, and other
products.
3.Used in medical diagnosis
4.Used to treat thyroid disorders. (Graves’s disease).
5.Used in molecular biology and genetics research.
6.Used in nuclear medicine for lung ventilation and blood flow studies.
7.Used in dental fixtures like crowns and dentures to provide a Uranium-234 natural color and brightness.
8.Used in electric blanket thermostats and to gauge the thickness of thin plastics, thin sheet metal, rubber, textile and paper.
water boils at 100 degrees celsius at sea level. If the water in this experiment did not boil to 100 degrees celsius, what could the reason be?
Answer:
It depends on how high you are above sea level
Explanation:
I did an experiment in my Scince class that showed, the less air that is around water will lessen it’s boiling level. We put water in a glass beaker inside of our vacuum chamber, we made a vacuum in he chamber. Making a vacuum is like being on a mountain, the less air the lower the boiling point. The water then began to boil due to the water evaporating. When we reached to maximum vacuum that we could the water started to boil at 61°C. No the water was not very hot, it was just warm water that just so happened to also be boiling, cool right!!! Anyways, we played with dry ice the next day.
Hoped this helped.
Hope I earned your star rating or helpful rating from this.
the air pressure around the experiment is lower than at sea level
what kind of investigations allow for the control of variables?
The experimental investigations allow for the control of variables.
What is control of variables?The control of variables is the experimental element that remains constant and unchanged throughout the experiment of the investigation.
The control of variables is held constant during the experiment to test the relation between the dependent and independent variables.
Thus, An experimental investigation allows the control of variables all the time.
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Which of the following industries is leaching used in?
To separate a metal from its ore using acid and preserving desirable products such as gold.
To separate a mixture of ethanol and water
To separate a slurry containing chalk and water
None of the above.
Answer:
To separate a metal from its ore using acid and preserving desirable products such as gold.
Explanation:
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4HCl(g)+O2(g)⟶2Cl2(g)+2H2O(g) Calculate the number of grams of Cl2 formed when 0.385 mol HCl reacts with an excess of O2. mass: g
The number of grams of Cl2 formed when 0.385 mol HCl reacts with an excess of O2 is 13.6675 g.
What are moles?A mole is defined as 6.02214076 × [tex]10^{23}[/tex] of some chemical unit, be it atoms, molecules, ions, or others. The mole is a convenient unit to use because of the great number of atoms, molecules, or others in any substance.
Given data:
Moles of hydrochloric acid = 0.385 mol
Mass of chlorine gas =?
Chemical equation:
4HCl + O₂ → 2Cl₂ + 2H₂O
Now we will compare the moles of Cl₂ with HCl.
HCl : Cl₂
4 : 2
0.385 : 2÷4× 0.385 = 0.1925 mol
Oxygen is present in excess that's why the mass of chlorine produced depends upon the available amount of HCl.
Mass of Cl₂ :
Mass of Cl₂ = moles × molar mass
Mass of Cl₂ =0.1925 mol × 71 g/mol
Mass of Cl₂ = 13.6675 g
Hence, the number of grams of Cl2 formed when 0.385 mol HCl reacts with an excess of O2 is 13.6675 g.
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Sunspot populations quickly rise and more slowly fall on an irregular cycle about every 11 years. Significant variations of the 11-year period are known over longer spans of time. For example, from 1900 to the 1960s the solar maxima (the period of greatest activity in the solar cycle of the sun) trend of sunspot count has been upward; from the 1960s to the present, it has diminished somewhat. The Sun is presently at a markedly heightened level of sunspot activity and was last similarly active over 8,000 years ago.
The number of sunspots correlates with the intensity of solar radiation over the period (since 1979) when satellite measurements of absolute radiative flux were available. Since sunspots are darker than the surrounding photosphere it might be expected that more sunspots would lead to less solar radiation and a decreased solar constant. However, the surrounding margins of sunspots are hotter than the average, and so are brighter; overall, more sunspots increase the sun's solar constant or brightness. During the Maunder Minimum in the 17th Century there were hardly any sunspots at all. The Maunder Minimum is the name given to the period roughly from 1645 to 1715, when sunspots became exceedingly rare, as noted by solar observers of the time. It is named after the solar astronomer Edward W. Maunder (1851-1928) who discovered the dearth of sunspots during that period by studying records from those years. During one 30-year period within the Maunder Minimum, for example, astronomers observed only about 50 sunspots, as opposed to a more typical 40,000-50,000 spots. This coincides with a period of cooling known as the Little Ice Age.
1) Which of the following is a true statement?:
A. There were more sunspots in 1965 than in 1701
B. The Little Ice Age had nothing to do with sunspots
C. The Sun is presently at a low level of sunspot activity
D. No one is counting sunspot activity any more
The Sun is presently at a low level of sunspot activity. Hence, option C is correct.
What is solar radiation?Solar radiation is often called the solar resource for the electromagnetic radiation emitted by the sun.
The Sun is presently at a low level of sunspot activity is the correct answer.
Hence, option C is correct.
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If 13.0 g of MgSO4⋅7H2O is thoroughly heated, what mass of anhydrous magnesium sulfate will remain?
6.349 g mass of anhydrous magnesium sulfate will remain.
What are moles?A mole is defined as 6.02214076 × 1023 of some chemical unit, be it atoms, molecules, ions, or others. The mole is a convenient unit to use because of the great number of atoms, molecules, or others in any substance.
Molar mass MgSO₄.7 H₂O = 246.52 g/mol
[tex]Moles =\frac{mass}{molar \;mass}[/tex]
[tex]Moles =\frac{13.0 g}{246.52}[/tex]
0.0527 moles
Molar mass MgSO₄ = 120.4 g/mol
Mass of anhydrous magnesium sulfate :
( 0.0527 x 120.4 ) => 6.349 g
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Activity 1.3 Put an unlit incense stick in a corner of your class. How close do you have to go near it so as to get its smell? Now light the incense stick. What happens? Do you get the smell sitting at a distance? Record your observations.
what are the condition for a gas like carbon (II) oxide to obey the gas laws?
Answer:
I don't know the answer, but I can give options :)
Explanation:
A gas such as carbon monoxide would be most likely to obey the ideal gas law at:
Option 1) High temperatures and low pressure.
Option 2) Low temperatures and high pressure.
Option 3) High temperatures and high pressure.
Option 4) Low temperatures and low pressure.
Answer:
The gas must occupy 0 volume at -273°celcius
Design a controlled experiment to test your hypothesis. A controlled experiment is one that only tests one variable. All other variables must remain the same. Make a drawing below that shows how you will set up your experiment. Then, write a description of the one factor that will vary and the two factors that will remain the same.
The problem is not found here but a possible experiment might be to measure the amount of product from a chemical reaction.
What is an experiment?An experiment is a procedure used to verify a working hypothesis obtained by applying the scientific method.
Experimental variables that can be tested include, for example, temperature, amount of product from a chemical reaction, etc.
In conclusion, the problem is not found here but a possible experiment might be to measure the amount of product from a chemical reaction.
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