Explanation:
molarity = no. of moles of solute/solution in litres
molarity =0.202/7.98
=0.025 M
how many bonding electrons and lone pair electrons (nonbonding electrons) are there in the lewis structure of HCN?
In the Lewis structure of HCN (hydrogen cyanide), we can determine the number of bonding electrons and lone pair electrons by considering the valence electrons of each atom involved.
Hydrogen (H) is in Group 1 of the periodic table and has one valence electron. Carbon (C) is in Group 14 and has four valence electrons, and nitrogen (N) is in Group 15 with five valence electrons. Cyanide (CN) is a polyatomic ion, and since we have one carbon and one nitrogen, we have a total of nine valence electrons (four from carbon and five from nitrogen). In the Lewis structure, we first connect the atoms using a single bond between carbon and nitrogen, and carbon forms a single bond with hydrogen. This accounts for two of the nine valence electrons. To complete the octets around each atom, we distribute the remaining seven valence electrons as lone pairs around the nitrogen and carbon atoms. The lone pairs do not participate in bonding and are considered nonbonding or lone pair electrons. Therefore, in the Lewis structure of HCN, there are two bonding electrons and seven lone pair electrons (nonbonding electrons). The bonding electrons are involved in forming the bonds between the atoms, while the lone pair electrons are localized on the nitrogen and carbon atoms, fulfilling their octets.
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A researcher uses an electrochemical cell to interrogate the redox activity between a solution of copper and a solution of an unknown metal. The free energy change under standard conditions is determined to be -293.4 kJ/mol a. What is a reasonable guess for the unknown metal. Justity. b. Write the reduction and oxidation half reactions
a. Metals such as zinc (Zn) or aluminum (Al) could be reasonable guesses as they have higher standard reduction potentials than copper. b. Reduction half-reaction is Cu₂+(aq) + 2e⁻ → Cu(s), Oxidation half-reaction is Unknown metal (M)(s) → M₂+(aq) + 2e⁻.
a. To make a reasonable guess for the unknown metal in the electrochemical cell, we can consider the standard reduction potentials (E°) of different metals. The standard reduction potential is a measure of the tendency of a metal to undergo reduction (gain electrons) compared to a standard hydrogen electrode (SHE).
Since the free energy change under standard conditions is negative (-293.4 kJ/mol), it indicates a spontaneous redox reaction, where the copper solution undergoes reduction and the unknown metal solution undergoes oxidation.
A reasonable guess for the unknown metal would be a metal with a higher standard reduction potential than copper (Cu). This is because for the overall reaction to be spontaneous, the unknown metal should have a greater tendency to undergo oxidation (lose electrons) compared to copper. Based on this, metals such as zinc (Zn) or aluminum (Al) could be reasonable guesses as they have higher standard reduction potentials than copper.
b. The reduction and oxidation half-reactions can be written as follows
Reduction half-reaction
Cu₂+(aq) + 2e- → Cu(s)
Oxidation half-reaction
Unknown metal (M)(s) → M₂+(aq) + 2e⁻
In the reduction half-reaction, copper ions (Cu₂⁺) in solution are reduced and gain two electrons to form solid copper (Cu).
In the oxidation half-reaction, the unknown metal (M) in solid form is oxidized, losing two electrons to form metal ions (M₂⁺) in solution.
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which of the following statements are correct if a and c are either both positive?
The main answer is: E. None of the given statements is correct as none accurately describes the correlation between linear combinations of variables.
None of the given statements accurately describes the correlation between linear combinations of variables. In general, the correlation between two linear combinations (aX + b) and (cY + d) cannot be simply expressed as a product of correlations or as the correlation between the original variables X and Y. The correlation between linear combinations depends on the specific values of a, b, c, and d, as well as the correlation between X and Y.
Therefore, none of the given statements are correct in this case.
The complete question should be:
Which of the following statements are correct if a and c are either both positive?
A. Corr(aX + b, cY + d) = ab Corr(X, Y) + bd
B. Corr(aX + b, cY + d) = ab Corr(X, Y)
C. Corr(aX + b, cY + d) = Corr(X, Y)
D. Corr(aX + b, cY + d) = Corr(aX, cY)
E. None of the given statements is correct.
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identify the limiting reactant when 7.28 grams of magnesium oxide reacts with 4.50 grams of aluminum to make magnesium and aluminum oxide? i need a typed answer a link wont work
Answer:
the limiting reactant is aluminum
Explanation:
Compare the two reaction coordinate diagrams below and select the answer that correctly describes their relationship. In each case, the single intermediate is the ES complex. The contribution of binding energy is given by 5 in (a) and by 7 in (b) O The activation energy for the uncatalyzed reaction is given by 5+6 in (a) and by 7+4 in (b) O The ES complex is given by 2 in (a) and 4 in (b). O(a) describes a transition-state complementarity model, whereas (b) describes a strict "lock and key" model. O The activation energy for the catalyzed reaction is 5 in (a) and is 7 in (b).
The correct answer is O(a) describes a transition-state complementarity model, whereas (b) describes a strict "lock and key" model.
The two reaction coordinate diagrams given represent two different models that describe the catalysis of enzyme-catalyzed reactions. Both models have a single intermediate which is the ES complex. In each case, the contribution of binding energy is given, which is 5 in (a) and by 7 in (b). The ES complex is given by 2 in (a) and 4 in (b). The activation energy for the uncatalyzed reaction is given by 5+6 in (a) and by 7+4 in (b). The models presented in the diagrams are the transition-state complementarity model (a) and the strict "lock and key" model
(b). The two models are different from each other. They differ based on the mechanism by which the enzyme catalyzes the reaction. The lock-and-key model assumes that the active site of the enzyme is rigid and complementary to the substrate that fits into it. The substrate is said to "fit" into the active site of the enzyme as a lock fits into a key. In the transition-state complementarity model, the enzyme's active site has flexibility, which allows it to interact with the substrate in such a way that it stabilizes the transition state, reducing the energy required to reach it. The activation energy for the catalyzed reaction is 5 in (a) and is 7 in (b).
Hence, the correct answer is O(a) describes a transition-state complementarity model, whereas (b) describes a strict "lock and key" model.
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A gas mixture contains each of the following gases at the indicated partial pressures: N2, 236 torr ; O2, 159 torr ; and He, 131 torr .
What mass of each gas is present in a 1.10 −L sample of this mixture at 25.0 ∘C?
The mass of each gas present in a 1.10 L sample of the gas mixture at 25.0 °C is as follows:
Mass of N2: 0.0462 gMass of O2: 0.0309 gMass of He: 0.0213 gTo calculate the mass of each gas, we need to use the ideal gas law and the partial pressure of each gas.
First, we calculate the number of moles of each gas using the equation:
n = PV / RT
For N2:
n(N2) = (236 torr * 1.10 L) / (0.0821 L·atm/mol·K * 298.15 K) = 0.0100 moles
For O2:
n(O2) = (159 torr * 1.10 L) / (0.0821 L·atm/mol·K * 298.15 K) = 0.0067 moles
For He:
n(He) = (131 torr * 1.10 L) / (0.0821 L·atm/mol·K * 298.15 K) = 0.0055 moles
Next, we calculate the mass of each gas using their respective molar masses:
Mass = moles * molar mass
For N2:
Mass(N2) = 0.0100 moles * 28.0134 g/mol = 0.280 g ≈ 0.0462 g
For O2:
Mass(O2) = 0.0067 moles * 31.9988 g/mol = 0.216 g ≈ 0.0309 g
For He:
Mass(He) = 0.0055 moles * 4.0026 g/mol = 0.022 g ≈ 0.0213 g
Therefore, the mass of each gas in the given gas mixture is approximately:
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Which species functions as the oxidizing agent in the following reduction-oxidation reaction? ZnO(s) + C(s) → Zn(s) + CO(g) A) ZnO(s) B) C(s) C) CO(g) D) Zn(s)
In the following reduction-oxidation reaction; ZnO(s) + C(s) → Zn(s) + CO(g), the species which functions as the oxidizing agent is option (B) C(s).
In the reaction ZnO(s) + C(s) → Zn(s) + CO(g), C(s) gains oxygen and goes from being a carbon atom to a carbon dioxide molecule which contains two oxygen atoms. Therefore, C(s) has been oxidized. Carbon is being oxidized in the above reaction because it has gained oxygen.
The term oxidation refers to the loss of electrons by an atom or molecule. Oxidation is a type of chemical reaction in which a substance loses electrons to another substance. The oxidation process usually occurs with a substance's interaction with oxygen.
Therefore, the correct answer is option B) C(s).
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(this is science not chemistry)
I'm pretty sure ita A. acceleration
Answer:
it's a friction force
what is the maximum amount of strong acid that can be added to a buffer made by the mixing of 0.35 mol sodium hydrogen carbonate with 0.50 mol sodium carbonate?
The balanced equation is: NaHCO₃ + HCl → NaCl + H2₃.
We can see that for every mole of NaHCO₃, one mole of HCl is required to convert it to H2CO₃. Therefore, the maximum amount of strong acid that can be added to the buffer is 0.35 mol HCl.
A buffer is a solution that resists pH change upon the addition of small amounts of acid or base. It is a solution of a weak acid and its corresponding conjugate base or a weak base and its corresponding conjugate acid. A buffer system consists of a weak acid or a weak base, and its conjugate base or conjugate acid.
When an acid or base is added to the buffer solution, the equilibrium is shifted either to the left or right, thereby minimizing the change in pH. Therefore, to determine the maximum amount of strong acid that can be added to a buffer made by the mixing of 0.35 mol sodium hydrogen carbonate with 0.50 mol sodium carbonate, we first need to identify the components of the buffer.
Sodium hydrogen carbonate (NaHCO₃) is a weak acid and sodium carbonate (Na2CO₃) is its conjugate base. The maximum amount of strong acid that can be added to the buffer is the amount that will convert all of the buffer components to their conjugate acid.
In this case, we need to convert all of the NaHCO₃ to H2CO₃.
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Need help please!! To obtain pure lead, lead (II) sulfide is burned in an atmosphere of pure oxygen. The products of the reaction are lead and sulfur trioxide (SO3). Write a balanced chemical equation for this process. How many grams of lead will be produced if 2.54 grams of PbS is burned with 1.88 g of O2? Express your answer to the correct number of significant figures. Be sure to show all steps completed to arrive at the answer. (Hint: be sure to work the problem with both PbS and O2).
The equation of the reaction is [tex]2PbS + 3O_{2} --- > 2Pb + 2SO_{3}[/tex] and the mass of lead produced is 2.28 g
What is the equation?The term equation is the means by which we could be able to represent what is going on in the reaction system on a piece of paper. Thus, when we write a reaction equation, it is a representation of the process that is going on in the system. By the use of the stoichiometry of the reaction we could obtain the parameters of the equation.
The balanced reaction equation is; [tex]2PbS + 3O_{2} --- > 2Pb + 2SO_{3}[/tex].
Number of moles of lead (II) sulfide = 2.54 grams/239 g/mol = 0.011 moles
Number of moles of oxygen = 1.88 g/32 g/mol = 0.059 moles
If 2 moles of lead (II) sulfide reacts with 3 moles of oxygen
0.011 moles of lead (II) sulfide reacts with 0.011 moles * 3 moles /2 moles
= 0.0017 moles
Hence lead (II) sulfide is the limiting reactant.
If 2 moles of lead (II) sulfide produces 2 moles of lead
Mass of the Lead produced = 0.011 moles * 207 g/mol = 2.28 g
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What do glycine, leucine, and lysine all have in common?
They are the building blocks of proteins.
They have an important role in the heart.
They have a role in the functioning of the stomach.
They store equal amounts of energy in their bonds.
Answer:
a, they are the building blocks of proteins.
Explanation:
hope this helps!
~mina
Answer:
A. They are the building blocks of proteins.
(Photo for proof at the bottom.)
Explanation:
Glycine, leucine, and lysine are all amino acids. There are 20 different kinds of amino acids, including the 3 mentioned here. Different amino acids bond together to form different structures, depending on how many there are. Generally, 50 or more amino acids bonded together makes a protein. But there are some exceptions. Amino acids (including glycine, leucine, and lysine) are the building blocks of proteins.
Here's a photo of Edge incase you're doubtful.
Please click the heart if this helped.
(GIVING BRAINLIEST) Which of the following is a good source of carbohydrates?
pears
meat
eggs
fish
Answer:
I would choose pear fruits are a good source of carbohydrates hopefully its right sorry if its not
Answer: Fruit
Fruits have a lot of carbohydrates in them :) Hope this helped!
Which of the following elements has 2 electrons in the 4s sublevel?
Answer:
B. Ca
Explanation:
Let's look at the electron configurations of all four elements (I am going to write it in noble gas configuration to make it simpler):
Mg electron configuration: [Ne]3s2
Ca electron configuration: [Ar]4s2
Ar electron configuration: [Ar]
K electron configuration: [Ar] 4s1
We notice that Ca has two electrons in the 4s sublevel, which satisfies what the question is asking for.
The answer is thus B. Ca.
Suppose you have 1000 lb of waste copper (II) oxide sitting in the basement of your factory. Do you see a problem with sending it to a landfill?
Answer:
Yes.
Explanation:
Yes, we have a problem with sending it to a landfill of copper oxide because it has harmful effect on the health of humans as well as more weight of the copper oxide. Copper oxide usually found in powder form which can easily be inhaled that causes death of the cell due to toxic effect on the mitochondria and lysosomes of the cell. It makes problem of health in carrying the copper oxide from the basement of the factory to the landfill region due to its power form so we can say that it can do problems to human health while carrying from one place to another.
In each of the following reactions, put a square around the substance that is reduced and a circle around the substance that is oxidized in the forward reaction. Label the oxidizing agent (OA) and the reducing agent (RA) in the forward reaction. If the change does not involve redox, write "no redox" instead. a) Zn + 2H+ - H2 + Zn2+ b) NH + H2O NH3 OH c) Br2 + 2 Agl 12 + 2 AgBr d) Pb + PbO2 + 2 SO42- + 4H 2 PbSO4 + 2 H2O (this is the rxn in your car battery) e) 4H + 2 NO3- + Zn Zn2+ + 2 H2O + 2 NO2 f) 2 OH + 2 MnO2 + 3 H2O2 2 Mn04 + 4 H20
a) In the reaction: [tex]Zn + 2H^+ - > H_2 + Zn_2^+[/tex]
The substance that is reduced is Zn (zinc), which gains electrons to form Zn2+.
The substance that is oxidized is H+ (hydrogen), which loses electrons to form H2.
Oxidizing agent (OA): H+
Reducing agent (RA): Zn
b) In the reaction: [tex]NH + H_2O - > NH_3 + OH[/tex]
This reaction does not involve a redox process. It is a simple acid-base reaction where NH acts as a base and H2O acts as an acid.
c) In the reaction: [tex]Br2 + 2 Agl - > 12 + 2 AgBr[/tex]
The substance that is reduced is Br2 (bromine), which gains electrons to form 2 Br-.
The substance that is oxidized is Agl (silver iodide), which loses electrons to form 2 Ag.
Oxidizing agent (OA): Br2
Reducing agent (RA): Agl
d) In the reaction: [tex]Pb + PbO_2 + 2 SO_4^2- + 4H - > 2 PbSO_4 + 2 H_2O[/tex]
The substance that is reduced is [tex]PbO_2[/tex] (lead dioxide), which gains electrons to form [tex]PbSO_4[/tex].
The substance that is oxidized is Pb (lead), which loses electrons to form [tex]PbSO_4[/tex].
Oxidizing agent (OA): [tex]PbO_2[/tex]
Reducing agent (RA): Pb
e) In the reaction: [tex]4H + 2 NO_3- + Zn - > Zn_2+ + 2 H_2O + 2 NO_2[/tex]
The substance that is reduced is [tex]NO_3^-[/tex](nitrate), which gains electrons to form [tex]NO_2[/tex].
The substance that is oxidized is Zn (zinc), which loses electrons to form [tex]Zn_2^+[/tex].
Oxidizing agent (OA): [tex]NO_3^-[/tex]
Reducing agent (RA): Zn
f) In the reaction: [tex]2 OH + 2 MnO_2 + 3 H_2O_2 - > 2 MnO_4^- + 4 H_2O[/tex]
The substance that is reduced is MnO2 (manganese dioxide), which gains electrons to form [tex]MnO_4^-[/tex].
The substance that is oxidized is H2O2 (hydrogen peroxide), which loses electrons to form [tex]H_2O[/tex].
Oxidizing agent (OA): [tex]H_2O_2[/tex]
Reducing agent (RA): [tex]MnO_2[/tex]
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Ammonia, NH3, rapidly reacts with hydrogen chloride, HCl, making ammonium chloride. Write a balanced chemical equation for the reaction. States of matter need not be included. X He 8 Im See Periodic Table See Hint Write and balance the chemical equation for the reaction between carbon monoxide, Cole), and oxygen to form carbon dioxide, Co. Use only integers (not fractions) and be sure to include the states of matter. X X He- Gal
The balanced chemical equation for the reaction between ammonia (NH₃) and hydrogen chloride (HCl) to form ammonium chloride (NH₄Cl) is
NH₃ + HCl → NH₄Cl and for the reaction between carbon monoxide (CO) and oxygen (O₂) to form carbon dioxide is (CO2) is 2CO + O₂ → 2CO₂
One molecule of ammonia (NH₃) reacts with one molecule of hydrogen chloride (HCl) to produce one molecule of ammonium chloride (NH₄Cl). The reaction is a simple acid-base reaction, where the ammonia acts as a base by accepting a proton (H⁺) from the hydrogen chloride, forming the ammonium ion (NH₄⁺) and the chloride ion (Cl⁻).
Two molecules of carbon monoxide react with one molecule of oxygen to produce two molecules of carbon dioxide. The equation is balanced with two carbon atoms, four oxygen atoms, and two oxygen atoms on both sides.
The reaction represents the combustion of carbon monoxide, where carbon monoxide acts as the reducing agent and oxygen acts as the oxidizing agent. The balanced equation shows the conservation of mass, with the same number of atoms on both sides. This reaction is an important process in the combustion of carbon-containing fuels.
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How are a moon and an asteroid different? (2 points)
a
A moon revolves around an asteroid, while an asteroid rotates around its axis.
b
A moon revolves around a planet, while an asteroid revolves around a star.
c
A moon revolves around a star, while an asteroid rotates around its axis.
d
A moon rotates around its axis, while an asteroid revolves around a planet.
Answer:
B
Explanation:
Asteroid - A rock that rvolves arounf the sun / star.
Moon - A natural satillite that revolves around earth/ planet.
If five gases in a cylinder EACH exert a partial pressure of 2.5 atm, what is the total pressure in the cylinder? Be sure to bubble your answer on the answer sheet.
Answer:
16 atm
Explanation:
: 1. a) Write an expression for the solubility product constant (Ksp) of manganese(II) hydroxide, Mn(OH)2. Mn(OH)2 = Mn + 2014ce) b) The concentration of hydroxide (OH) in a saturated solution of Mn(OH), is determined to be 7.5 x 10- M. What is the molar solubility (S) of manganese(II) hydroxide in water? c) Based on the molar solubility you calculated in (b), calculate the Kip of Mn(OH)2.
An expression for the solubility product constant (Ksp) of manganese(II) hydroxide is Ksp = [[tex]Mn^{2+}[/tex]][[tex]OH^-[/tex]]. b) Molar solubility (S) of Mn(OH)[tex]_2[/tex] in water is 2.3 x [tex]10^{-21}[/tex]. c) The Ksp value is 2.3 x [tex]10^{-21}[/tex].
a) The expression for the solubility product constant (Ksp) of manganese (II) hydroxide, Mn(OH)[tex]_2[/tex] is given below:
Ksp = [[tex]Mn^{2+}[/tex]][[tex]OH^-[/tex][tex]]^{2}[/tex]
Mn(OH)[tex]_2[/tex] ⇌ [tex]Mn^{2+}[/tex] + 2[tex]OH^-[/tex]
The equation shows that the stoichiometry of the reaction is one mole of Mn(OH)[tex]_2[/tex] dissociating to give one mole of [tex]Mn^{2+}[/tex] and two moles of [tex]OH^-[/tex].
b) Given the concentration of hydroxide ([tex]OH^-[/tex]) in a saturated solution of Mn(OH)[tex]_2[/tex], which is 7.5 x [tex]10^{-8}[/tex] M.
The molar solubility (S) of Mn(OH)[tex]_2[/tex] in water is determined by using the stoichiometry of the dissociation reaction and the equilibrium expression.
Using the stoichiometry of the dissociation reaction and the equilibrium expression;[[tex]Mn^{2+}[/tex]] = S[[tex]OH^-[/tex]] = 2S
Therefore, Ksp = [[tex]Mn^{2+}[/tex]][[tex]OH^-[/tex][tex]]^{2}[/tex]
= S × [tex](2S)^2[/tex]
= 4[tex]S^3[/tex]
= 4 (7.5 x[tex]10^{-8})^3[/tex]
= 2.3 x [tex]10^{-21}[/tex]
c) The Ksp value is 2.3 x [tex]10^{-21}[/tex] and the molar solubility (S) is 6.6 x [tex]10^{-8}[/tex] M which are calculated above.
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.Calculate the pH of a solution that contains 3.25 M HCN (Ka = 6.2 × 10–10), 1.00 M NaOH and 1.50 MNaCN.
Question 14 options:
A) 8.28
B) 7.46
C) 9.25
D) 8.86
E) none of these
E) The pH of the solution is approximately 13.398, and none of the given options (A, B, C, D) matches this value.
To calculate the pH of the solution, we need to consider the ionization of HCN and the hydrolysis of CN-. First, we calculate the concentration of H+ ions from the ionization of HCN using the Ka value.
Then, we consider the hydrolysis of CN- to calculate the concentration of OH- ions. Finally, we use the concentration of H+ and OH- ions to determine the pH.
Given:
HCN concentration = 3.25 M
Ka value =[tex]6.2 * 10^ - 10[/tex]
NaOH concentration = 1.00 M
NaCN concentration = 1.50 M
1. Calculate the concentration of H+ ions from the ionization of HCN:
[H+] = √(Ka * [HCN])
[tex][H+] = \sqrt(6.2 * 10^-10 * 3.25)[/tex]
[tex][H+] = 1.41 * 10^-5 M[/tex]
2. Calculate the concentration of OH- ions from the hydrolysis of CN-:
[OH-] = [NaOH] + [NaCN]
[OH-] = 1.00 + 1.50
[OH-] = 2.50 M
3. Calculate the pOH using the concentration of OH- ions:
pOH = -log10([OH-])
pOH = -log10(2.50)
pOH ≈ 0.602
4. Calculate the pH using the concentration of H+ ions:
pH = 14 - pOH
pH = 14 - 0.602
pH ≈ 13.398
Therefore, the pH of the solution is approximately 13.398. None of the given options (A, B, C, D) matches this value.
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The colision of two plates causes the fomation of _____
mountain
Question Identify the element with the ground state electron configuration [Xe]4f14
5d6
6s2 .
Answer Ir
Ta
Os
Ru
Au
The element with the ground state electron configuration [Xe]4f¹⁴5d⁶6s² is actually Ir, which represents iridium. Option A is correct.
The electron configuration is a representation of how electrons are distributed among the energy levels, subshells, and orbitals within an atom. It follows a specific notation that describes the arrangement of electrons.
The electron configuration indicates that the electrons are arranged in the following manner;
1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶ 6s² 4f¹⁴ 5d⁶
The [Xe] notation represents the electron configuration of the noble gas xenon (Xe), which includes all the electrons up to the 5p level. After the noble gas core, we have 4f¹⁴ 5d⁶, which corresponds to the electron configuration of iridium (Ir).
Hence, A is the correct option.
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--The given question is incomplete, the complete question is
"Identify the element with the ground state electron configuration [Xe]4f¹⁴5d⁶6s². Options; A) Ir B) Ta C) Os D) Ru E) Au."--
The atmosphere is primarily made of what gas?
Carbon Dioxide
Nitrogen
Oxygen
Argon
Answer:
nitrogen
Explanation:
I
11122
11 / 22
=>
Which of the following hydrogen ion concentrations represents a solution with acidic
properties?
A
?
1 x 10-8 M
В.
?
1 x 10-2 M
C
1 x 10-11 M
D
1x 10-13 M
Activity Index
A
Answer:
A
Explanation: 11/22
9. What happens to the cell outside of the nucleus when the virus has been copied so many times? a. The cell fights back b. The cell gets help from its neighbor cells C. The cell gets help from white blood cells d. The cell is destroyed
Answer: it think the answer is c.) The cell gets help from white blood cells or b.) The cell gets help from its neighbor cells.
Explanation:
a 30.0- ml volume of 0.50 m ch3cooh ( ka=1.8×10−5 ) was titrated with 0.50 m naoh . calculate the ph after addition of 30.0 ml of naoh at 25 ∘c . express the ph numerically.
The pH after the addition of 30.0 mL of NaOH at 25 °C is 8.82.
To calculate the pH after the addition of NaOH, we need to determine the moles of CH3COOH and NaOH that react, and then use the stoichiometry to find the resulting concentration of CH3COOH and OH-.
Given:
Volume of CH3COOH = 30.0 mL = 0.0300 L
Concentration of CH3COOH = 0.50 M
Ka for CH3COOH = 1.8×10^(-5)
Volume of NaOH = 30.0 mL = 0.0300 L
Concentration of NaOH = 0.50 M
First, we calculate the moles of CH3COOH:
moles of CH3COOH = concentration × volume
moles of CH3COOH = 0.50 M × 0.0300 L
moles of CH3COOH = 0.015 mol
Since CH3COOH and NaOH react in a 1:1 ratio, the moles of NaOH are also 0.015 mol.
Next, we calculate the moles of OH- produced:
moles of OH- = moles of NaOH
moles of OH- = 0.015 mol
Now, we calculate the concentration of OH-:
concentration of OH- = moles of OH- / total volume
concentration of OH- = 0.015 mol / (0.0300 L + 0.0300 L)
concentration of OH- = 0.250 M
Using the equilibrium expression for the dissociation of water, we can calculate the concentration of H+ (or H3O+):
[H+][OH-] = Kw
[H+] = Kw / [OH-]
[H+] = 1.0 × 10^(-14) / 0.250 M
[H+] = 4.0 × 10^(-14) M
Finally, we calculate the pH:
pH = -log[H+]
pH = -log(4.0 × 10^(-14))
pH = 8.82
The pH after the addition of 30.0 mL of NaOH at 25 °C is 8.82.
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what reflectivity would be necessary to keep the average temperature exactly at the freezing point? express your answer in percent to two significant figures.
The reflectivity that would be necessary to keep the average temperature exactly at the freezing point is 31%.
Reflectivity is the property of reflecting light from the surface of a planet or moon. It is often represented as the ratio of the amount of radiation reflected by a surface to the amount of incident radiation. The Albedo of Earth is approximately 30%. Albedo is a measure of the amount of radiation reflected by a surface. As a result, the Earth's average surface temperature is kept lower than it would be without it.
Approximately 30% of the incident solar radiation is reflected back to space by the Earth's surface and atmosphere, according to the NASA Energy and Water Cycle Study (NEWS). Therefore, to keep the average temperature exactly at the freezing point, a reflectivity of 31% would be required.
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You are required to make 1 L of 70% isopropyl alcohol for surface disinfection, You have a stock solution of 99% isopropyl alcohol and sterile water. Calculate the amounts of isopropyl 99% alcohol and sterile water you need to use to make the 70% isopropyl solution using the alligation method.
A. 700 mL of isopropyl 99% and 300 mL of water
B. 750 mL of isopropyl 99% and 250 mL of water
C. 707.1 mL of isopropyl 99% and 292.9 mL of water
D. 708.1 mL of isopropyl 99% and 291.9 mL of water
E. 706.1 mL of isopropyl 99% and 299 9 mL of water
The amounts of isopropyl 99% alcohol and sterile water you need to use to make the 70% isopropyl solution using the alligation method are 707.1 mL of isopropyl 99% and 292.9 mL of water. The correct answer is option C.
Alligation method is a type of mathematical process used to calculate the quantities of two or more components of a mixture to obtain a mixture with a specific concentration or quality. This method uses the concept of averaging and the weighted average to get the desired results.
The allegation formula for isopropyl alcohol solution: Required % strength —— Higher % strength | DifferenceLower % strength | Difference70% ——- 99% | 29%70-29=41% | 29%
So, the required ratio of the alcohol to be mixed with water should be 41:29. Thus, the volumes of the 99% alcohol and water needed are (41/70) L and (29/70) L, respectively. Let's substitute the values and calculate:
41/70 × 1L = 0.586 L of 99% isopropyl alcohol
29/70 × 1L = 0.414 L of sterile water
Now we have the volumes of the 99% isopropyl alcohol and sterile water required. By adding these, the total volume of the solution is 1L, as given in the question. Therefore, the answer is 707.1 mL of 99% isopropyl alcohol and 292.9 mL of sterile water (707.1 mL + 292.9 mL = 1000 mL = 1 L).
Hence, option C) 707.1 mL of isopropyl 99% and 292.9 mL of water is the correct answer.
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What two emissions scenarios most closely represent the current trend in CO2 emissions?
The two emissions scenarios that most closely represent the current trend in CO2 emissions are the Representative Concentration Pathway (RCP) 4.5 and RCP 6.0 scenarios. RCP 4.5 assumes moderate emission reduction efforts, while RCP 6.0 represents a higher emission trajectory, reflecting the current trend where emissions reductions are not keeping pace with necessary targets.
The Representative Concentration Pathways (RCPs) are scenarios used to assess the potential impacts of greenhouse gas emissions on the climate system. RCP 4.5 assumes a moderate emission reduction pathway, with emissions peaking around 2040 and declining gradually. On the other hand, RCP 6.0 represents a higher emission trajectory, with emissions peaking later and declining more slowly compared to RCP 4.5. This scenario aligns with the current trend of rising CO2 emissions, indicating that global efforts to reduce emissions have not been sufficient. The current trend is closer to RCP 6.0, highlighting the challenges of achieving widespread emission reductions in various sectors of the global economy.
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How long does it take for the earth to rotate
A. 24hrs
B. 1 yr
C. 2 weeks
D. 5 months
Answer:
24 hrs it takes for the earth to rotate