The half-life of iodine-123 is 13.3 hours. How much of a 25.0 mg sample will remain after 39.9 hours?
A. 3.12 mg
B. 6.25 mg
C. 1.56 mg
D. 25.0 mg
E. 12.5 mg

The wavelength (in nanometers) of an electron in an atom of hydrogen transitioning in energy is 486nm.

The expression for the wavelength of radiation is:

1/λ = \(R(\frac{1}{n^{2}_{1} } -\frac{1}{n^{2}_{2} })\)

Substitute values in the above expression,

1/λ = 109677 * \((\frac{1}{2^{2} } - \frac{1}{4^{2} })\) = 109677 * \((\frac{1}{4} -\frac{1}{16} )\) = 109677 * \((\frac{12}{64} )\)

λ=4.86 * \(10^{-5}\) = 486 * \(10^{-9} m\) = 486nm.

Transitions between orbitals that are further apart in energy produce light with higher energy and therefore higher frequency. Emits ultraviolet photons. The step from the second energy level to the third energy level is much smaller. The energy required for this jump is only 1.89 eV. The energy of hydrogen atoms depends on the energy of electrons. When the electron changes levels, its energy decreases, and the atom emits a photon.

When an electron moves from a higher energy level to a lower energy level a photon is emitted. It has electrons bound to the nucleus. The energy of hydrogen atoms depends on the energy of electrons. When the electron changes levels, its energy decreases, and the atom emits a photon. A photon is emitted while an electron moves from a higher energy level to a lower energy level. A hydrogen atom's electrons must be in one of the allowed energy levels.

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Answer:

C option

Explanation:

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The amount of heat that is required to melt 5.50 mol of gallium at 1 atm pressure is 33 kJ/mol.

Given that,

Gallium sublimation heat = 277 kj/mol

Gallium vaporization heat = 271 kj/mol

Sublimation, as we know, transforms a sold substance into a gas. Changing from a liquid to a gas is called vaporization.                                        

Hence, using the provided Data, we can derive two equations;

Ga (s)  --> Ga (g) delta, Heat = 277 kJ/mol

Ga (l)  --> Ga (g) delta Heat = 271 kJ/mol

Ga (s) --> Ga (l) delta H = 6 kJ/mol is the result of differentiating these two equations to determine the amount of heat needed to melt one mol.

Therefore, it takes 6 kJ/mol of heat to melt one mol of gallium.

Therefore, 5.5 x 6 = 33 kJ/mol of heat is needed to melt 5.5 mol of gallium.

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\(\huge\fcolorbox{red}{pink}{Answer ♥}\)

The carbon atom is unique among elements in its tendency to form extensive networks of covalent bonds not only with other elements but also with itself. ... Moreover, of all the elements in the second row, carbon has the maximum number of outer shell electrons (four) capable of forming covalent bonds.

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The balanced chemical equation for the reaction between magnesium (Mg) and oxygen (O2) to form magnesium oxide (MgO) is:

2Mg (s) + O2 (g) → 2MgO (s)

In this equation, there are 2 atoms of magnesium and 2 molecules of oxygen on both sides of the equation, which means the equation is balanced.

This is an example of a synthesis reaction, where two or more substances combine to form a new compound. In this case, magnesium and oxygen react to form magnesium oxide. The reaction is exothermic, which means that it releases heat. This reaction is commonly used in the production of magnesium oxide, which is a useful material in various industrial applications, such as refractory linings in furnaces and kilns.

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Balance the chemical equation Mg (s) + O2 (g) → MgO (s) and identify type of reaction.

The balanced chemical equation for the formation of magnesium oxide (MgO) from the interaction of magnesium (Mg) and oxygen (O2) is 2Mg (s) + O2 (g) (s).

As there are two magnesium atoms and two oxygen molecules on either side of the equation in this case, the equation is balanced.

This is an illustration of a synthesis reaction, in which two or more chemicals come together to create a brand-new compound. As a result of this reaction, magnesium and oxygen produce magnesium oxide. Because the process is exothermic, heat is given off. Magnesium oxide is a result of this reaction that is frequently utilised in a variety of industrial applications, such as refractory linings for furnaces and kilns. Chemical symbols are used in chemical equations to represent what happens during a chemical reaction.

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Balance the chemical equation Mg (s) + O2 (g) → MgO (s) and identify type of reaction.

Answer:

B. Food can be produced in larger amounts for more people to eat.

Explanation:

Commercial farming mechanizes operations controls diseases and pests, enabling farms to produce more

Answer:

food can be produced in larger amounts for more people to eat.

Explanation:

you're welcome

The correct answer is Oe. Thermal capacitance, with respect to a tank process, is defined as the product of the mass of the tank wall and the specific heat capacity of the material of the tank wall.

Thermal capacitance refers to the ability of a system or object to store thermal energy. In the context of a tank process, the tank wall plays a significant role in storing and releasing heat. The thermal capacitance of the tank is determined by the mass of the tank wall and the specific heat capacity of the material composing the tank wall.

The greater the mass of the tank wall and the higher the specific heat capacity of the material, the higher the thermal capacitance of the tank.

Thermal capacitance refers to the ability of a system or object to store thermal energy. In the case of a tank process, the thermal capacitance is determined by the tank wall's characteristics.

The tank wall acts as a barrier between the contents of the tank and the surrounding environment. When the tank is subjected to heating or cooling, the tank wall absorbs and stores thermal energy. This stored energy helps maintain the temperature of the tank's contents.

The thermal capacitance of the tank is calculated by multiplying the mass of the tank wall by the specific heat capacity of the material composing the tank wall. The mass represents the amount of material present in the tank wall, while the specific heat capacity indicates the amount of heat energy required to raise the temperature of the material.

By understanding the thermal capacitance of the tank, engineers can determine how much heat energy is needed to raise or lower the temperature of the tank's contents and how long it will take for the tank to reach a desired temperature. This knowledge is crucial for designing and optimizing tank processes in various industries, such as chemical processing, food production, and energy storage.

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Answer

1.0 mol

Explanation

Given:

Volume, V = 5.0 L

Temperature, T = 215 K

Pressure, P = 342 kPa

The gas constant, R = 8.31 L kPa/mol K

What to find:

The number of moles of the gas sample.

Step-step-solution:

The number of moles of the gas can be determine using the ideal gas equation formula:

Put the given values into the formula and calculate for n:

The number of moles of the gas sample is 1.0 mol.

Answer: A

Explanation: I hope this helps!

Answer:

A or C. Best to go with A

Explanation:

Hope it works!!

Answer:

Image

Explanation:

An electrolytic solution is a solution that has the ability of conducting electricity. Electrolytic solutions contain ions in which it conducts electricity from those ions. Ions are charged atoms. This solution (refer to image) has ions, as represented by the + and - symbols.

Answer:

The new moles of the gas in the flask is 2.13 moles.

Explanation:

Given;

number of moles of gas, n = 1.9 mol

temperature of the gas, T = 21 °C  = 21 + 273 = 294 K

pressure of gas, P = 697 mmHg

volume of gas, V = ?

Apply ideal gas law;

PV = nRT

Where;

R is gas constant, = 62.363 mmHg.L / mol. K

V = nRT / P

V = (1.9 x 62.363 x 294) / 697

V = 49.98 L

New pressure of the gas, P = 795 mmHg

New temperature of the gas, T = 26 °C = 273 + 26 = 299 K

New moles of the gas, n = ?

Volume of the gas is constant because volume of the flask is the same when more gas was added.

n = PV / RT

n = (795 x 49.98) / (62.363 x 299)

n = 2.13 moles

Therefore, the new moles of the gas in the flask is 2.13 moles.

Salt is soluble in water.

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From thermal comfort point of view, thick walled structures are beneficial in hot and humid climates is the statement that is true.The correct option is C.

Thick walled structures are beneficial in hot and humid climates from the thermal comfort point of view.How do thick walled structures help in hot and humid climates - In hot and humid climates, thick walls tend to absorb the heat present in the environment. This absorption helps to keep the interior of the structure cool.

Additionally, thick walls take more time to heat up and more time to cool down. Thus, in hot and humid climates, thick walls are a better choice than thin walls because they provide thermal comfort.

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Noble gas configuration for Li : [He]2s¹

In an atom, there are levels of energy in the shell and sub-shell

This energy level is expressed in the form of electron configurations.

Lithium with atomic number 3, then the electron configuration:

1s²2s¹

And for noble gas configuration or it can be called Condensed electron configurations :

[He]2s¹

Answer:

[He]2s¹

Explanation:

Explanation:

The most common hot dipping process for industrial applications is galvanizing, which refers to the coating of zinc over iron or steels for rust proofing. It is an extremely versatile and easy means of providing corrosion protection for construction materials exposed to atmospheric conditions

Answer: Decrease the pressure.

Explanation: There is more room for the gas to move around. They won't hit the wall of the container as much and since temperature is constant, pressure drops.

Answer:

evaluation

Explanation: Big brain

Answer:

i dont even know tbh jk i wont waste ur time unless nvm ok so the answer is The correct answer would be C.10. Krebs cycle is a part of cellular respiration that takes place in the mitochondria. Five energy conversions take place in one complete cycle of the Krebs cycle. These conversions lead to the formation of three molecules of NADH, one molecule of FADH₂ and one molecule of ATP.

Explanation:bc im superrr smart

Answer:

its actually B i got it right on my edge exam

Explanation: i dont  know why they put c.

Most of the positively charged particles should bounce back at a range of angles as they collide with the atoms in the foil; only a few should pass straight through the foil.

Answer: Nuclear fusion is a nuclear reaction where atomic nuclei of a low atomic number fuse to form a heavier nucleus releasing energy.

Explanation:

Answer:A radioactive sample emits the most radiation as soon as it is formed or isolated. The reason is that that is when the concentration of the radioactive material is the greatest. It begins to decay immediately and as it does, the concentration of radioactive material in the sample gets less.

Explanation:

Answer:

thermal shock

Explanation:

the temperatures inside the glass jar should have continued to increase over time. Internal stresses due to uneven heating. This is also known as “thermal shock”.

In general, the thicker the glass, the more prone it will be to breaking due to the immediate differences in temperature across the thickness of glass.

Borosilicate glass is more tolerant of this, as it has a higher elasticity than standard silicon glass.

You may also note that laboratory test tubes and flasks are made with thinner walls, and of borosilicate glass, when designated for heating.

When a neutron is fired into one of 100 atoms of uranium-235, it can cause a chain reaction.

Uranium-235 is an isotope of uranium that is fissile, meaning it can undergo nuclear fission. When a neutron collides with a uranium-235 nucleus, it causes the nucleus to become unstable and break apart into two smaller nuclei and several additional neutrons. These additional neutrons then go on to collide with other uranium-235 nuclei, causing them to undergo fission as well, releasing more neutrons in the processThis process of neutron-induced fission can continue, releasing large amounts of energy in the form of heat and light, as well as radiation. The chain reaction can be controlled or made to stop by adding or removing neutrons from the system, making the neutron to nucleus collision less likely to occur.In a nuclear power plant, the chain reaction is controlled and the heat generated by the fission reactions is used to produce steam, which drives turbines to generate electricity. In a nuclear weapon, the chain reaction is uncontrolled, resulting in a much larger release of energy in a much shorter period of time.

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Answer:

NaNO3

balanced equation - Na2CO3 + Sn(NO3)2 → 2NaNO3 + Sn(CO3)

In order to help the learner categorize the material, the following inquiry is best:" Is the material malleable or ductile?".

What is a malleable material?

Any substance that can be easily hammered into a thin sheet is bendable. The metal that is most malleable is gold. In contrast, ductility refers to a solid material's capacity to deform when subjected to tensile stress.

A ductile substance is what?

The capacity of a material to be hammered thin or stretched into wire without breaking is known as its ductility. You can draw a ductile material into a wire. The majority of metals, including gold, silver, copper, erbium, terbium, and samarium, are excellent examples of ductile materials.

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Questions:

A student is trying to classify an unidentified, solid gray material as a metal or a nonmetal. Which question will best help the student classify the material? A. Is the material malleable or ductile? B. Does the material feel hard to the touch? C. Will the material float in water? D. Does the material feel rough or smooth?

Answer:

the answer is C

Explanation:

Record the time to complete a chemical reaction

The step that will be part of a lab procedure is; "Record the time to complete a chemical reaction."

A lab procedure refers to something that is done in the laboratory as part of an experiment.

If we look at the options carefully, we will notice that the only thing that is part of a laboratory experiment is "Record the time to complete a chemical reaction."

This action can be carried out in a live lab procedure.

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The value of E° for the reaction: Ti²⁺(aq) + Zn(s) → Ti(s) + Zn²⁺(aq) is -0.87 V, using the given standard reduction potentials.

We know that E° for Zn²⁺(aq) = -0.76 V and E° for Ti²⁺(aq) = -1.63 V. Now, to determine E° for the reaction: Ti²⁺(aq) + Zn(s) → Ti(s) + Zn²⁺(aq), using the given standard reduction potentials we need to:-

1. Identify the oxidation and reduction half-reactions:-
  Oxidation: Zn(s) → Zn²⁺(aq) + 2e⁻ (Zn loses electrons)
  Reduction: Ti²⁺(aq) + 2e⁻ → Ti(s) (Ti gains electrons)

2. Use the given standard reduction potentials to find the corresponding standard oxidation potentials:-
  E° for Zn(s) → Zn²⁺(aq) = -(-0.76 V) = 0.76 V
  E° for Ti²⁺(aq) + 2e⁻ → Ti(s) = -1.63 V

3. Add the standard oxidation and reduction potentials to find the overall E° for the reaction:-
  E° = E°(oxidation) + E°(reduction)
  E° = 0.76 V + (-1.63 V)
  E° = -0.87 V

Therefore, the E° for the reaction Ti²⁺(aq) + Zn(s) → Ti(s) + Zn²⁺(aq) is -0.87 V.

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Answer:

a.

84,791 » 8479

b.

256.75 » 256.8

c.

431,801 » 4318

d.

0.00078100 » 0.0007810

Explanation:

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