Which solution below has the highest concentration of hydroxide ions?a. pH= 3.21b. pH= 7.00c. pH= 7.93d. pH= 12.59e. pH= 9.82

Answer:

Explanation:

For every hal-life time the amount of the radioisotope (fluorine-18) will be cut to half.

Part a.

Since the half-life of fluorine-18 is 110 min, ater this very time, half of the fluorine-18 is still alive, i.e 100. mg / 2 = 50.0 mg. ← answer

Part b.

Compute the time elapsed from 8:00 am, when the fluorine-18 is shipped, to 1:30 pm, when the sample arrives at teh radiology laboratory.

Compute the number of half-lives in 330 min:

Conclusion:

After one half-life of 110 minutes, 50mg of the 100mg of Fluorine-18 would remain. After the time interval of 5 hours and 30 minutes or 330 minutes, which constitutes three half-lives, the remaining active Fluorine-18 would be 12.5mg.

In the case of Fluorine-18, the half-life is 110 minutes. This essentially means that half of the original amount of the radioisotope will decay and become inactive in 110 minutes.

a. If 100mg of Fluorine-18 is shipped at 8:00 a.m., after 110 minutes (or 1 hour and 50 minutes), at 9:50 a.m., half of the original amount, 50mg, will still be active.

b. If 100mg of Fluorine-18 is shipped at 8:00 a.m., and it arrives at the radiology laboratory at 1:30 p.m., this is 5 hours and 30 minutes, or 330 minutes later. As the half-life is 110 minutes, this period encompasses three half-lives (330/110). Starting with 100mg, after one half-life it would be 50mg, after the next it would be halved to 25mg, and after the third it would be 12.5mg remaining active.

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Answer:

Nitrogen atom

Explanation:

Hence;

c= 1.4 X [tex]10^-^4[/tex] is the composition and ph of an ideal buffer prepared from lactic acid ([tex]CH_3CHOHCO_2H[/tex]), where the hydrogen atom highlighted in boldface is the acidic hydrogen atom.

A buffer is a solution that can resist pH change upon the addition of an acidic or basic components.

Equilibrium equation

[tex]C_3H_6O_3[/tex] ⇄[tex]C_3H_5O_3^-[/tex] +[tex]H^+[/tex]

Assuming a degree of dissociation [tex]\alpha[/tex] =[tex]\frac{1}{10}[/tex]

And the initial concentration of [tex]C_3H_6O_3[/tex] =c

At equlibrium ;

Concentration of [tex]C_3H_6O_3[/tex] = [tex]c - c\alpha[/tex]

[tex]C_3H_5O_3^-[/tex] = [tex]c\alpha[/tex]

[[tex]H^+[/tex]] = [tex]c\alpha[/tex]

[tex]Ka =\frac{c\alpha X c\alpha }{c-c\alpha }[/tex]

[tex]\alpha[/tex] is very small so 1-[tex]\alpha[/tex] can be neglected and the equation is;

[tex]Ka = c\alpha X \alpha[/tex]

[H^+] = [tex]c\alpha[/tex] =[tex]\frac{k\alpha }{\alpha }[/tex]

pH = -log [[tex]H^+[/tex]]

pH = -log[tex]Ka[/tex] +log [tex]\alpha[/tex]

[tex]Ka[/tex] = 1.38 X [tex]10^{-4}[/tex]

[tex]\alpha[/tex] = [tex]\frac{1}{10}[/tex]

pH = 3.86 -1

pH =2.86

Composition ;

C=[tex]\frac{1}{\alpha }[/tex] X [tex][H^+][/tex]

[tex][H^+][/tex] =0.0014

c= 0.0014 X [tex]\frac{1}{10}[/tex]

c= 1.4 X [tex]10^-^4[/tex]

Hence, c= 1.4 X [tex]10^-^4[/tex] is the composition and ph of an ideal buffer prepared from lactic acid ([tex]CH_3CHOHCO_2H[/tex]), where the hydrogen atom highlighted in boldface is the acidic hydrogen atom.

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An ideal buffer composed of lactic acid involves a mixture of lactic acid and its conjugate base, usually in equal molar amounts. Using the Henderson-Hasselbalch equation, the resulting pH will be close to 3.86, which is the pKa value of lactic acid.

The composition and pH of an ideal buffer prepared from lactic acid (CH3CHOHCO2H), would involve a mixture of lactic acid and its conjugate base, sodium lactate (CH3CHOHCO2Na). By using the Henderson-Hasselbalch equation, pH = pKa + log([A-]/[HA]), where pKa is the negative logarithm of Ka and [A-]/[HA] represents the ratio of the concentration of the conjugate base to the acid, we can determine the pH. For an ideal buffer, the ratio should be close to 1:1 to maintain a pH close to the pKa of lactic acid.

As an example, assume a student has mixed an equal number of moles (not necessary for equal weights as molar masses differ) of lactic acid and sodium lactate. In this case, since the pKa of lactic acid is 3.86, the resulting buffer would ideally have a pH close to 3.86, given that the concentrations of lactic acid and sodium lactate are similar after mixing.

Answer:

[tex]\boxed{\text{(B)}}[/tex]

Explanation:

CaF₂(s) ⇌ Ca²⁺(aq) + F⁻(aq); ΔH > 0

According to Le Châtelier's Principle, when a stress is applied to a system at equilibrium, the system will respond in a way that tends to relieve the stress.

Let's consider each of the stresses in turn.

(A) Evaporating some of the water

The concentrations of the ions will increase, so calcium fluoride will precipitate out to remove the stress (the Ca²⁺ and F⁻ ions). The position of equilibrium does not shift, and [Ca²⁺] stays the same.

(B) Adding HNO₃

HF is a weak acid, so F⁻ is a relatively strong base. The added HNO₃ will convert the F⁻ ions to HF, removing them from solution. More CaF₂ will dissolve to replace the F⁻ ions, and this will add more Ca²⁺ ions as well. The position of equilibrium will shift to the right, and [Ca²⁺] will increase.

(C) Adding NaNO₃(aq)

There is no common ion, so NaNO₃ will have no effect. The added water will dilute the solution and decrease the concentrations of the ions. However, more CaF₂ will dissolve to increase the concentrations. The position of equilibrium does not shift, and [Ca²⁺] stays the same.

(D) Adding NaF

This is the common ion effect. F⁻ is the common ion. The added NaF will dissolve, increasing the concentration of F⁻ ions. More CaF₂ will precipitate to remove the added F⁻ ions, but it removes Ca²⁺ ions at the same time. The position of equilibrium shifts to the left, and [Ca²⁺] decreases.

the law of thermodyanamic is the restatement of the law of conservation of energy

Answer:

Lets the total pressure is Pt and the individual gases are designated as pH2, pCO2, pNe, pO2.

Pt =  pCO2+ pNe+pO2+ pH2

285KPa = 13 KPa+ 14 KPa + 157 KPa +pH2

Now add the partial pressure of CO2, Ne and O2 which is equal to 184 KPa.

285 KPa = 184 KPa + pH2  

Now subtract the individual pressure of each gas from thje total pressure.

285 KPa - 184 KPa = pH2

                101 KPa = pH2

The partial pressure of hydrogen is  101 KPa.

Answer:

2H₂ + O₂ → 2H₂O.

Explanation:

2H₂ + O₂ → 2H₂O.

So, every 2.0 moles of H₂ react with 1.0 mole of O₂ to produce 2.0 moles of H₂O.

The balanced equation of the reaction is:

[tex]\underline{2}H_2\ +\ \underline{1}O_2\ \rightarrow \underline{2}H_2O\\[/tex]

A balanced equation must have equal numbers of moles of the various element on both sides of the equation.

Now, lets us analyze the given equation. This is show below:

[tex]\_H_2\ +\ \_O_2\ \rightarrow \_H_2O\\[/tex]

Reactants:

Products:

From the above, it is obviously clear that the equation is not balanced.

Therefore, the equation can be balanced by writing 2 before hydrogen gas, H₂ and 2 before water, H₂O as shown below:

[tex]\underline{2}H_2\ +\ \underline{1}O_2\ \rightarrow \underline{2}H_2O\\[/tex]

Now, we can say that the equation is balanced.

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Answer:

the dotted line showing the intermolecular attraction

Explanation:

Answer:

1. P₂O₅      → oxidation number of phosphorous is +5 and Oxygen is -2.

2. (SO₄)²⁻ → oxidation number of sulfur is +6 and Oxygen is -2.

3. KClO₃   → oxidation number of Potassium is +1, Chlorine is +5, and Oxygen is -2.

4. NH₄Cl  → oxidation number of Nitrogen is -3, Hydrogen is +1, and Chlorine is -1

5. (NH₄)₂S  → oxidation number of Nitrogen is -3, Hydrogen is +1, and Sulfur is -2

Explanation:

General Rules for assigning oxidation numbers

The oxidation number of a free element is always 0.

The oxidation number of a mono-atomic ion equals the charge of the ion.

The alkali metals (group I) always have an oxidation number of +1.

The alkaline earth metals (group II) are always assigned an oxidation number of +2.

Oxygen almost always has an oxidation number of -2, except in peroxides (H₂O₂) where it is -1 and in compounds with fluorine (OF₂) where it is +2.

Hydrogen has an oxidation number of +1 when combined with non-metals, but it has an oxidation number of -1 when combined with metals.

The algebraic sum of the oxidation numbers of elements in a compound is zero.

The algebraic sum of the oxidation states in an ion is equal to the charge on the ion.

Using the above rules:

1. P₂O₅

∵ it is a neutral compound its total charge is 0.

Also, we know that oxygen has an oxidation number of -2.

Let oxidation number of P be x

∴ 2(x)+5(-2)=0   →   2x=+10   →   x=+5  

∴oxidation number of phosphorous is +5.

2. SO₄²⁻:

∵ it is a charged ion its total charge is -2.

Also, we know that oxygen has an oxidation number of -2.

Let oxidation number of S be x

∴ (x)+4(-2)= -2   →   x=+6  

∴oxidation number of sulfur is +6.

3. KClO₃:

∵ it is a neutral compound its total charge is 0.

Also, we know that oxygen has an oxidation number of -2 and the  oxidation number of K (group I) is +1

Let oxidation number of Cl be x

∴ (+1) + (x) + 3(-2) = 0   →   x=+5  

∴oxidation number of Chlorine is +5.

4. NH₄Cl:

∵ it is a neutral compound its total charge is 0.

Also, we know that chloride has an oxidation number of -1

Hydrogen has an oxidation number of +1 when combined with non-metals

 Let oxidation number of N be x

∴ (x) + 4(+1) + (-1) = 0   →   x=-3  

∴oxidation number of Nitrogen is -3.

5. (NH₄)₂S:

∵ it is a neutral compound its total charge is 0.

Also, we know that chloride has an oxidation number of -1

Ammonium ion (NH₄⁺) has an oxidation number of +1

 Let oxidation number of N be x

∴ 2(+1) + (x) = 0   →   x= -2  

∴oxidation number of sulfur is -2.

Answer:

14.68 moles of He

Explanation:

To do this, just remember Avogadro's Constant or Avogadro's number. This constant tells us how many units ( in this case atoms) there are in a mole of ANY type of substance.

Avogadro's constant is 6.022140857 × 10²³ units per mole.

Now that we know how many atoms there are in 1 mole, we can use this as our conversion factor.

8.84 x 10²⁴ atoms of He →  moles of He

[tex]8.84\times10^{24} atoms of He\times\dfrac{1moleofHe}{6.022140857\times10^{23}atomsofHe}=14.68molesofHe[/tex]

So the answer would be:

14.68 moles of He

Answer:

A. O, S, Se

Explanation:

If you look up Oxygen (O), Sulfur (S) and Selenium (Se) in the periodic table, you will see that these three fall under the same column. In the periodic table, elements are arranged in rows and columns. Columns are called groups. The elements that fall under the same group share similar chemical properties.

The elements given above are all in Group VIA or group 16.

Answer:

The higher the pH is, the more the hydroxide ion concentration increases and the more basic the solution becomes.

Explanation:

Answer:

B

Explanation:

Answer:

1.05 x 10^-6

Explanation:

Lambda = c / f

f if frequency

c is intensity of light

lambda = 3 x 10^8  / 2.85 x 10^14

             = 1.05 x 10 ^-6

D. I hope you have a good morning

- Josie Annette

The molecule C3H6 is classified as a Alkene.

The answer is alkene

Answer:

Explanation:

The influence of temperature in equilibrium reactions can be predicted from the heat (enthalpy) information.

This is the chemical reaction:

The information about the enthalpy of the reaction, ∆H = − 92.2 kJ,  indicates that energy (heat) has been released to the surroundings (the products of the forward reaction have less energy than the reactants), which is defined as an exothermic reaction.

Then, you can rewrite the equaition in the form:

This is, the heat can be seen as a product of the direct reaction (or a reactant of the reverse reaction).

Now, it is quite straight to apply  Le Chatelier's principle:

a) Decreasing temperature is equivalent to extract heat or having less heat on the left side.

b) Then, the equilibrium must shift in a way that this lack of heat is compensated. Then, the reaction will shift to the right to produce more heat.

As conclusion, you can tell that in exothermic reactions, a decrase in temperature will cause the equilibrium to shift to the right.

This shift, of course, means the production of more ammonia.

The other choices are discarded following this brief reasoning:

1. increase the velocity of the gas molecules: the average velocity of the particles increases when the average kinetic energy increases, and the average kinetic energy will decrease if the temperature decreases. So, this statement is false.

3. increase the kinetic energy of the gas molecules: no, the average kinetic energy is proportional to the temperature, then reducing the temperature decreasese the average kinetic energy.

4. produce less ammonia: it was shown that reducing the temperature will produce more ammonia.

5. have no effect: no, it does have effect, as shown.

In the Haber process of ammonia production, when the reaction temperature is decreased, more ammonia is produced due to the exothermic nature of the reaction following Le Chatelier's Principle. The velocity and kinetic energy of the gas molecules decrease. Real-world ammonia production also accounts for pressure and catalyst factors.

The reaction of nitrogen and hydrogen to form ammonia, otherwise known as the Haber process, is an exothermic process, meaning it releases heat. As per Le Chatelier's principle, lowering the temperature of an exothermic reaction at equilibrium favors the production of more products. Therefore, decreasing the temperature of the hydrogen and nitrogen reaction will produce more ammonia (option 2).

Simultaneously, as we decrease the temperature, the average kinetic energy of the gas molecules decreases and, hence, the speed of the gas molecules also decreases. Therefore, the statement that decreasing the temperature will increase the velocity of the gas molecules (option 1) and increase the kinetic energy of the gas molecules (option 3) are incorrect. The option that decreasing the temperature will have no effect (option 5) is also incorrect in this scenario.

In real-world applications, the production of ammonia via the Haber process is influenced by pressure and temperature changes, and also by the usage of a catalyst to overcome the reaction's slow rate at lower temperatures.

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The idea that atoms are unstable would have been strengthened because the orbiting electron would lose energy and fall into the nucleus.

Answer:

The idea that atoms are unstable would have been strengthened because the orbiting electron would lose energy and fall into the nucleus.

Explanation:

Based on classical mechanics an electron would spiral and fall on the nucleus thus collapsing the atom. But it was quantum mechanics that proposed that electrons move in definite orbits around the nucleus. Electrons absorb a definite quantum of energy and move from a lower state to an excited state. Also electrons release a definite quantum of energy and move from excited to more stable state.

Answer:

The answer is 5.3 because when looking at the moles produced from the coefficient from the balanced equation all you have to do is make the 6 on the left equal 8.  IN order to do that you multiply by 1 and 1/3, then do that to the number 4 to get 5.3

Explanation:

Answer:

Two functional groups

Explanation:

We have the carboxylic group and the amine group.

The COOH group to the left is the alkanoic acid/carboxylic acid group..

The NH₂ to the right is the amino functional group.

Answer:

the nucleus of the atom was centrally located i n the atom and was positively charged

Explanation:t

Answer:

the nucleus of the atom was centrally located in the atom and was positively charged

Explanation:

Electrons orbit outside the nucleus. Option A is incorrect.

Nucleus is positive in charge and is located at the center of the atom. Option B is correct.

The nucleus is positively  charged and that the electrons are negatively charged. Option C is incorrect.

Electrons do affect the properties of atoms. Option D is incorrect.

Answer:

Pb(NO₃)₂ ₍aq₎ + 2 KI ₍aq₎  ------------> PbI₂ ₍s₎ + 2 KNO₃ ₍aq₎

Explanation:

Chemical Equation:

lead(II) nitrate: Pb(NO₃)₂

potassium iodide: KI

lead(II) iodide: PbI₂

Potassium nitrate: KNO₃

Pb(NO₃)₂ ₍aq₎ + KI ₍aq₎  ------------> PbI₂ ₍s₎ + KNO₃ ₍aq₎

Balancing the equation:

For balancing the equation all atoms of the elements on both sides of equation i.e reactants and products are equal.

So balancing the above equation we get:

Pb(NO₃)₂ ₍aq₎ + 2 KI ₍aq₎  ------------> PbI₂ ₍s₎ + 2 KNO₃ ₍aq₎

Answer:

matter

Explanation:

Iron marks the boundary between fusion and fission for energy release. Lighter elements than iron release energy through fusion, while heavier elements release energy through fission. Iron has the highest binding energy per nucleon, making it a turning point on the energy-mass curve.

The element that marks the boundary between using fusion and fission to release energy is iron (Fe). In the context of nuclear reactions, fusion occurs when two light nuclei combine to form a heavier nucleus, releasing energy because the combined nucleus has a higher binding energy per nucleon.

In contrast, fission is the process of splitting a heavy nucleus into smaller nuclei, releasing energy because the products have a higher binding energy per nucleon than the original heavy nucleus.

Iron possesses the highest binding energy per nucleon, which is why it is an energy-increasing process to fuse nuclei lighter than iron. For elements heavier than iron, fission becomes an energy-releasing process. Thus, iron is a unique marker in the periodic table where the more energy-efficient method of releasing nuclear energy switches from fusion to fission.

Fusion is responsible for powering stars and for the creation of elements in the universe through a process known as nucleosynthesis. Furthermore, while fission has been utilized in nuclear weapons and reactors, fusion promises to release far more energy per reaction, making it an attractive but technically challenging energy source. On an energy-mass curve, nuclei to the left of iron release energy through fusion while those to the right produce energy through fission.

its c take the pressure away

The study of chemicals and bonds is called chemistry. There are different types of elements and these are metals and nonmetals.

The correct answer is option C which decreases the pressure over the liquid.

The mixing of solute in the solvent is called solubility.

Solubility of solute depends on these factors and these are:-

According to the question, solubility increases when the pressure in liquid decreases.

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Answer:

[Ar] 3d10 4s2 4p4

Explanation:

Answer: The electronic configuration of selenium is [tex][Ar]4s^23d^{10}4p^4[/tex]

Explanation:

Electronic configuration is the representation of electrons that are present in an element.

Selenium is the element which is present in Group 16 and has an atomic number of 34.

Atomic number is defined as the number of protons or number of electrons present in an atom.

The number of electrons present in this element is 34.

So, the electronic configuration of selenium = [tex]Se:[Ar]4s^23d^{10}4p^4[/tex]

Answer:

I think D

Explanation:

Q > Ksp,  there are more ions in solution than are necessary for saturation. This is a supersaturated solution (i.e There is a tendency for the extra solute to precipitate).

nutrition reaction or saline reaction because these reactions generate salts , such as:

HCl + NaOH==>NaCl + H2O

Answer and Explanation:

Answer: C. An increase in food availability increases the birth rate in the population.

Explanation:

The conveying limit of a biological system can be characterized as the greatest size of a populace of an animal types an environment can uphold based on accessibility of assets, for example, food, water, living space and different necessities.

An increase in food availability increases the birth rate in the population

is the right choice in light of the fact that to build the populace till the conveying limit there should be excess stock of food ought to be accessible to the populace which can uphold in expansion in birth rate so the populace can achieve a level at the conveying limit.

Answer:The biosphere is all life on our planet. ... The impact on climate is mainly due to the connection between the biosphere and the atmosphere. Processes such as photosynthesis and respiration naturally affect the concentrations of gases such as oxygen and carbon dioxide in the atmosphere.

Explanation:

In photosynthesis, plants constantly absorb and release atmospheric gases in a way that creates sugar for food. Carbon dioxide goes in the plant's cells; oxygen comes out. Without sunlight and plants, the Earth would become an inhospitable place unable to support air-breathing animals and people.

Answer:

Noble gases are the only type of element that are chemically inert, that is, they do not normally undergo chemical reactions with other elements under normal circumstances, this is because they are chemically stable. Their stability is as a result of the eight valence electrons that they have in their outermost shells.

Other elements usually try to attain the stability found in noble gases by undergoing chemical reactions and by forming different types of bonds with other elements. One of the chemical bonds that are usually formed is covalent bond. In simple covalent bond, two elements usually donate one electron each, the two electrons donated are then shared equally by the two of them in order to ensure that each one has eight electrons in its outermost shell.

Atoms achieve noble-gas electron configurations in single covalent bonds through the sharing of electrons between atoms.

Atoms achieve noble-gas electron configurations in single covalent bonds through the sharing of electrons between atoms.

In a covalent bond, electrons are shared between atoms, and generally, each atom contributes one or more electrons to the bond. The shared electrons are attracted by the nuclei of both atoms, resulting in a stable electron configuration.

For example, in a double covalent bond between two oxygen atoms (O=O), each oxygen atom contributes two electrons, resulting in a shared configuration that resembles the noble gas, neon.

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