21
Select the correct answer.
How many valence electrons does oxygen have?
OA 2
OB. 4
О с. 6
OD. 8
OE. 10
Answer: 6 valence electrons
Explanation: the atomic number for oxygen is 8. the first shell takes 2, the second 8. so, the outer shell is the last shell, which takes 6 from oxygen because oxygen has only 8. 6 is the number for outer or valence electron for oxygen
the energy of the H-H bond is 432 kJ/mol. The energy of the 0=0 is 498 kJ/mol. witch bond is weakest
The weaker bond is the bond between the two hydrogen atoms since it has a lower bond energy.
What is bond energy?The term bond energy has to do with the energy that is required to break a bond. It is also the energy that must be supplied when a bond is formed.
The lower the bond energy of bond, the weaker the bond. Hence, it follows that the weaker bond here is the bond between the two hydrogen atoms since it has a lower bond energy.
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What volume of a 3.50 M Na3PO4 solution would you use to make 1.50 L of a 2.55 M Na3PO4 solution?
A. 1.09 L
B. 2.06 L
C. 13.4 L
D. 0.917 L
Calculate the density of a liquid if 25.7g sample has a volume of 22.6mL
[tex]density = \frac{mass}{volume} [/tex]
[tex]d = \frac{25.7}{22.6} = 1.13717 \: g/ml[/tex]
[tex]pay \: attention \: to \: the \: unit \: used \: to \\ express \: the \: density \\ since \: the \: mass \: is \: given \: in \: grams \\ and \: volume \: in \: milliliter \: then \\ the \: density \: is \: expressed \: in \\ grams \: per \: \: milliliter[/tex]
PLEASE HELP!!!
What is the correct net ionic reaction for Pb(NO3)2(aq) +2NaI(aq) → PbI2(s) + 2NaNO3(aq)?
The net ionic equation of the reaction is:
Pb²⁺ (aq) +2 I⁻ (aq) → PbI2(s)What are net ionic equations?Net ionic equations are equations where ions which remain in solution known as spectator ions are not shown in the equation. Only ions involved in formation of product are shown.
In the given equation, sodium and nitrate ions are spectator ions.
The net ionic equation of the given reaction is as follows:
Pb²⁺ (aq) +2 I⁻ (aq) → PbI2(s)In conclusion, spectator ions are not shown in net ionic equation.
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Determine from the balanced chemical reaction if the derived moles ratio is correct or incorrect.
The molar ratio of (6 moles of NaBr)/(1 mole of Fe₂S₃) is correct based on the balanced chemical equation.
Balanced chemical reactionThe balanced chemical reaction is given as;
2FeBr₃ + 3Na₂S → Fe₂S₃ + 6NaBr
From the balanced chemical reaction above, 6 moles of NaBr will also correspond to 1 mole of Fe₂S₃.
Thus, the molar ratio of (6 moles of NaBr)/(1 mole of Fe₂S₃) is correct based on the balanced chemical equation.
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Oil from cashew nuts
Answer:
yes it's a thing, milk too
The answer to this question
1) There are only single bonds between the carbon atoms, so the ending is 'ane'. Thus, the answer is 2-methylbutane.
2) There is one triple bond between one pair of carbon atoms, so the ending is 'yne'. So, the answer is 2-butyne.
3) There is one double bond between one pair of carbon atoms, so the ending is 'ene'. So, the answer is 2-butene.
The specific heat of a certain type of cooking oil is 1.75 cal/(g ·°C). How much heat energy is needed to raise the temperature of 2.50 kg of this oil from 23 ∘C to 191 ∘C?
637,980 Joules is needed to raise the temperature of 2.50 kg of this oil from 23 ∘C to 191 ∘C.
What is specific heat?The heat in calories required to raise the temperature of one gram of a substance one degree Celsius.
Q = cmΔT
where
Q = heat energy needed for that material to get desired temperature change (in Joules)
M = mass (in grams) so you have to convert from kilograms.
c = specific heat constant for the material being heated
ΔT = change in temperature
Q = (1.75)(2.17 x 1000)(191 - 23)
Q = (1.75)(2170)(168)
Q = 637,980 Joules
Hence, 637,980 Joules is needed to raise the temperature of 2.50 kg of this oil from 23 ∘C to 191 ∘C.
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Which of the following statements is most accurate about how individual atoms produce light?
Group of answer choices
Electrons can spontaneously emit a photon of light without dropping to lower energy levels.
Light is not created by atoms, it just passes through them.
Photons are emitted when an electron jumps to higher energy levels in an atom.
An electron in an excited energy level of an atom will always drop to lower energy levels, emitting very specific wavelengths of light in the process.
Answer:
An electron in an excited energy level of an atom will always drop to lower energy levels, emitting very specific wavelengths of light in the process.
A red line is observed at 656.3 nm in the spectrum of atomic hydrogen. determine the values of ???? for the beginning and ending energy levels of the electron during the emission of energy that leads to this spectral line.
The beginning and ending energy levels of the electron during the emission of energy that leads to spectral line n(i)= 2 and n(f)=2
calculation :-(i) Calculation of energy of photon:-wavelength(λ) = 656.3 nm = 656.3 x 10^-9
E= hc / λ
E = energy of the photon
h=Planck's constant
c=speed of light
λ= wavelength of the photon
E= (6.626 x 10^-34)(3 x 10^8)/( 656.3 x 10^-9)
E = 3.028 x 10^-37J
(ii) Beginning and ending energy levels of the electron during the emission of energy that leads to this spectral line.It's a red line which means it falls in a visible region which is known as the Balmer series so;
n (f) = 2
ΔE= RH (1/n(f)^2 - 1/n(i)^2)
3.028 x 10^-37 =-2.18 x 10^-18(1/2^2 - 1/n(i))
n(i)= 2
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Part G
The compound Iron oxide can exist with either iron(II) ions or Iron(III) ions. Conduct Internet research to learn about the
differences between iron(II) oxide and iron(III) oxide. Give the chemical formula for each compound. Describe their
appearance and uses. Based on your findings, are these two forms of the same compound, or are they two completely
different compounds?
BIU xX² X₂
parameters
chemical formula
appearance
uses
10pt
V
iron(II)oxide
AvZv = = = = = = V V
Iron(III) oxide
Answer:
Therefore the theoretical density of iron is 7.877 g/cm³ .
Therefore the number of vacancy per cm³ is
Explanation:
what is entropy?
Answer this and Have a good day
Answer:
Entropy is a measurement of how much the atoms in a substance are free to spread out, move around, and arrange themselves in random ways
Here is the picture for the q plss help !!
When 400g each of water, oil, and sand are taken and heated from room temperature to 700⁰C on identical Bunsen burners. In this case, Substances that take more time to get heated will take more time to cool Hence, Option (A) is correct.
What is Heat transfer ?
Heat transfer is a form of energy transfer and can occur by conduction, convection, and/or radiation.
Heat transfer occurs any time there is a temperature difference between two objects and occurs in the direction of decreasing temperature, meaning from a hot object to a cold object.
Tests show that the transferred heat relies upon three factors—the adjustment of temperature, the mass of the framework, and the substance and period of the substance.
One of the significant impacts of heat transfer is temperature change: warming builds the temperature while cooling diminishes it.
We expect no stage change and no work is done on or by the framework.
In this case, Substances that take more time to get heated will take more time to cool Hence, Option (A) is correct.
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In the second equation FePO4 is an ionic compound. What is the charge on the Fe?
Answer:
+3
Explanation:
The phosphate ion has a charge of -3, so for the compound to have an overall change of 0, Fe needs to have a charge of +3.
Use the information and examples provided in the exploration to determine the maximum (theoretical) amount of CaCO3 in grams, that can be produced from the precipitation reaction
The maximum amount of CaCO3 we can expect is 0.0180 mole x 100 g/mole = 1.80 g.
Calculations and ParametersGiven that:
There would be a precipitate of calcium carbonate from the reaction between sodium carbonate and calcium chloride.
The reaction is:
Na2CO3 (aq) + CaCl2(aq) → CaCO3 (s) + 2 NaCl (aq)
2.00 g CaCl2 x 1 mole/ 111 g CaCl2
= 0.0180 mole CaCl2
Mix it with 2.00 g Na2CO3 x 1 mole/ 106 g
= 0.0189 mole Na2CO3
The maximum amount of CaCO3 we can expect is 0.0180-mole x 100 g/mole = 1.80 g
Therefore, the 1.80 g is the theoretical (calculated) yield of CaCO3 in this example.
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An intravenous saline solution contains 166 mEq/L each of Na+ and Cl−.
How many moles of Na+ are in 1.30 L of the saline solution?
The moles of Na⁺ in 1.30 L is 0.2158 moles of Na⁺.
What is concentration of a solution?Concentration of a solution is the amount of solute present in a given volume of solution or solvent.
The concentration of the Na⁺ in the intravenous saline solution contains 166 mEq/L.
1 mEq/Liter = 1 mmol/L
Moles of Na⁺ in 1.30 L = M
[tex]M = {166 mEq/L} * \frac{1 mmol/L}{1 mEq/L} * \frac{1.30 L}{1000 mL} = 0.2158\:moles[/tex]
Moles of Na⁺ in 1.30 L = 0.2158 moles of Na⁺.
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why neutron doesn't contain any charge?
Answer:
Neutron does not contain any charge because the charge of the quarks that made up the neutron balances each other out.
Hope it helps.
What is the density of a liquid with a mass of 6 grams, and a volume
of 3 milliliters?
Answer:
2 g/mL
Explanation:
Density can be calculated using the ratio:
Density = mass (g) / volume (mL)
Since you have been given both the mass and volume of the liquid, you can calculate the density.
Mass = 6 grams (g)
Volume = 3 milliliters (mL)
Density = mass / volume
Density = 6 g / 3 mL
Density = 2 g/mL
James was supposed to measure the circumference of three trees as homework for science class. When he got to class the next day, he realized that he measured the trees in inches instead of centimeters.
One tree had a circumference of 41 inches. What is the tree's circumference in centimeters?
Hint: 1 inch equals 2.5 cm
A.
102.5 cm
B.
27 cm
C.
135 cm
D.
16 cm
Answer:
[tex]\huge\boxed{\sf 102.5\ cm}[/tex]
Explanation:
Given that,
Circumference = C = 41 inches
Also,
1 inch = 2.5 cmMultiply 41 to both sides
41 inches = 2.5 × 41 cm
41 inches = 102.5 cm
So, The tree has a circumference of 102.5 cm.
[tex]\rule[225]{225}{2}[/tex]
If we want to study rest-frame visible light emitted by stars in distant galaxies at a high redshift of z 3, what portion of the electromagnetic spectrum do we need to observe? (hint JWST is meant to study distant galaxies)
The portion of the electromagnetic spectrum do we need to observe is the red part of the This is further explained below.
What is electromagnetic spectrum?Generally, Spectrum refers to the range of wavelengths or frequencies that electromagnetic radiation may cover.
In conclusion, We need to keep an eye on the red part of the electromagnetic spectrum since a large positive redshift causes an increase in wavelength and a corresponding fall in frequency and photon energy (such as light).
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A sample of gas is at a pressure of 2.81 atm, 664 K, and a volume of 713 L. What will
be the pressure of the gas if its volume and temperature change to 126 L, and 368 K
respectively? Please help explain
Answer:
8.81 atm
Explanation:
If we let the unknown pressure be x,
[tex] \frac{713 \times 2.81}{664} = \frac{126x}{368} \\ \\ x = 8.81[/tex]
Can someone please help me out? Its due by midnight tonight!!!!
Calculate the pH for the following weak acid.
A solution of HCOOH has 0.19M HCOOH at equilibrium. The Ka for HCOOH is 1.8×10−4 . What is the pH of this solution at equilibrium?
The pH of the solution is obtained as 2.23.
What is the pKa?The pKa shows the extent to which an acid is dissociated in solution. Now we have;
HCOOH(aq) + H2O(l) ⇔ HCOO-(aq) + H30+(aq)
Ka = [HCOO-] [ H30+]/[ HCOOH]
But = [HCOO-] = [ H30+] = x
Ka = x^2/[HCOOH]
x = √Ka [HCOOH]
x = √0.19 * 1.8×10−4
x = 5.8 * 10^-3
pH = - log (5.8 * 10^-3)
pH = 2.23
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A sample of gas has temperature of 372 K and pressure of 3.8 ATM. If the temperature is increased to 550 K, what is the new pressure?
Answer: The correct answer is 5.6atm.
Explanation: Since we only have information on the pressure and temperature, we will use Gay-Lussac's Law: [tex]\frac{P_{1} }{T_{1} } =\frac{P_{2} }{T_{2} }[/tex]. Now that we have the formula, let's plug in our given information!
[tex]\frac{3.8atm}{372K} =\frac{P_{2} }{550K}[/tex]
We must find the value [tex]P_{2}[/tex]. To do this, we will write a stoichiometric equation to solve this.
[tex]P_{2} =\frac{3.8atm*550K}{372K}[/tex]
Let's input the numbers into a scientific calculator to get our answer!
[tex]P_{2} =\frac{3.8atm*550K}{372K}=5.6 atm[/tex]
Given all of this work, the value [tex]P_{2}[/tex] equals 5.6 atm.
I hope this helps! Pls give brainliest!! :)
Use the ideas of the Kinetic Theory to explain the following. A sealed container contains nitrogen gas. The pressure of a gas is due to the molecules of the gas hitting the walls of the container. Explain why the pressure inside the container increases when the temperature is increased.
Answer:
When the temperature increases, the molecules of the gas gain energy. Therefore, they move faster.
This causes the molecules to hit the walls of the container more frequently and with greater force. Hence the pressure inside the container increases.
Tin(IV) sulfide, SnS2, a yellow pigment, can be produced using the following reaction.
SnBr4(aq)+2Na2S(aq)⟶4NaBr(aq)+SnS2(s)
Suppose a student adds 48.1 mL of a 0.478 M solution of SnBr4 to 48.8 mL of a 0.160 M solution of Na2S.
1) The theoretical yield of SnS2 will be 4.20 grams
2) The percent yield will be 7.93%
Percent yieldFrom the equation of the reaction:
[tex]SnBr_4(aq)+2Na_2S(aq)-- > 4NaBr(aq)+SnS_2(s)[/tex]
The mole ratio of the reactant is 1:2.
Mole of 48.1 mL, 0.478 M SnBr4 = 0.478 x 48.1/100 = 0.023 mols
Mole of 48.8 mL, 0.160 M Na2S = 0.160 x 48.8/1000 = 0.0078 moles
Thus, Na2S is in excess while SnBr4 is limiting.
Mole ratio of SnBr4 and SnS2 = 1:1
Equivalent mole of SnS2 = 0.023 moles
Mass of 0.023 noles SnS2 = 0.023 x 182.81 = 4.20 grams
2) With 0.0333 g of SnS2 recovered, percent yield = 0.333/4.2 x 100 = 7.93%
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Here is the complete question:
Tin(IV) sulfide, SnS2, a yellow pigment, can be produced using the following reaction.
SnBr4(aq)+2Na2S(aq)⟶4NaBr(aq)+SnS2(s)
Suppose a student adds 48.1 mL of a 0.478 M solution of SnBr4 to 48.8 mL of a 0.160 M solution of Na2S.
1) Calculate the theoretical yield of SnS2. ;
2) The student recovers 0.333 g of SnS2. Calculate the percent yield of SnS2 that the student obtained.
How would you solve
14x3-2x5=?
because if you take 42-10 = 32
32 is the answer to this question 14x3-2x5.
What is BODMAS?According to the BODMAS rule, if an expression contains brackets ((), {}, []) we have first to solve or simplify the bracket followed by 'order' (that means powers and roots, etc.), then division, multiplication, addition and subtraction from left to right.
14x3-2x5
42 -10
32
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A solution is prepared by dissolving 0.131 g of a substance in 25.4 g of water. The molality of the solution is determined by freezing point
depression to be 0.056 m. What are the moles of the substance?
The mole of the substance, given the data from the question is 0.0014 mole
What is molality?This is simply defined as the mole of solute per kilogram of water. Mathematically, it is expressed as
Molality = mole / mass (Kg) of water
How to determine the mole of the substanceMass of water = 25.4 g = 25.4 / 1000 = 0.0254 KgMolality = 0.056 mMole of substance =?Mole = molality × mass of water
Mole of substance = 0.056 × 0.0254
Mole of substance = 0.0014 mole
Thus, the mole of the substance is 0.0014 mole
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The half-life of the radioactive isotope magnesium-20 is 0.600 seconds.
How long will it take for the mass of a sample of magnesium-20 to decay from 65.6 micrograms to 8.20 micrograms?
____________seconds
It will take less 1.8 seconds for the mass of a sample of magnesium-20 to decay from 65.6 micrograms to 8.20 micrograms.
What is Half-Life of radioactive a radioactive substance?The half-life of a radioactive element is the time for half the amount of a sample of the substance to decay.
After 0.6 seconds 31.25 remains
After 1.2 seconds, 15.625 remains
After 1.8 seconds, 7.9 micrograms remains.
In conclusion, it will take less 1.8 seconds for the sample to decay to 8.20 micrograms.
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The time taken for the radioactive sample to decay is 1.8 s.
What is the half life?The half life is the time taken for only half of the number of the radioactive isotopes to remain. Now we have;
No = 65.6 micrograms
N = 8.20 micrograms
t1/2 = 0.600 seconds
t = ?
Hence;
N/No = (1/2)^t/t1/2
8.20/ 65.6 = (1/2)^t/0.600
0.125 = (1/2)^t/0.600
1/8 = (1/2)^t/0.600
(1/2)^3 = (1/2)^t/0.600
3 = t/0.600
t = 3 * 0.600
t = 1.8 s
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Sucrose decomposes to fructose and glucose in acid solution. When ln [sucrose] is
plotted vs. time, a straight line with slope of -0.208 hr-1 results. What is the rate law for
the reaction?
A) Rate = 0.208 hr-1 [sucrose]2
B) Rate = 0.208 hr-1 [sucrose]
C) Rate = 0.0433 hr [sucrose]2
D) Rate = 0.0433 hr [sucrose]
E) Rate = 0.208 mol L-1hr-1 [sucrose]0
The correct rate law for the reaction is given as Rate = -0.208 hr-1 [sucrose].
What is a first order reaction?A first order reaction is one in which a plot of the logarithm of the concentration against time gives a straight line graph. Now we know that this is a decomposition reaction thus the slope is negative.
Thus, in this case, the correct rate law for the reaction is given as Rate = -0.208 hr-1 [sucrose].
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