There are __________ moles of N atoms present in a 2.0 g C8H10O2N4.

The given question is incomplete, the complete question is:

Suppose the amount of a certain radioactive substance in a sample decays from 1.30 mg to 100. ug over a period of 29.5 days. Calculate the half life of the substance Round your answer to 2 significant digits.

Answer:

The correct answer is 7.974 days.

Explanation:

Based on the given question, the concentration of a radioactive substance present in a sample get decays to 100 micro grams from 1.30 milligrams in 29.5 days. There is a need to find the half-life of the substance.  

Radioactive decay is an illustration of first order reaction.  

K = (2.303 / t) log [a/(a-x)]

Here a is 1.30 mg and (a-x) is 100 micrograms = 100 * 10^-3 mg or 0.1 mg, and t is 29.5 days. Now putting the values we get,  

K = (2.303 /29.5)log (1.30/0.1)

= 2.303/29.5 log13

= 2.303/29.5 * 1.1139

K = 0.0869

The half-life or t1/2 is calculated by using the formula, 0.693 / K

= 0.693 / 0.0869

= 7.974 days.  

Answer:

Li>Na>K>Rb

Explanation:

Answer:

c. Li > Na > K > Rb

Explanation:

edge 2021

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Answer: 1. [tex]H^++OH^-\rightarrow H_2O[/tex]  Lewis acid : [tex]H^+[/tex], Lewis base : [tex]OH^-[/tex]

2. [tex]Cl^-+BCl_3\rightarrow BCl_4^-[/tex] Lewis acid : [tex]BCl_3[/tex], Lewis base : [tex]Cl^-[/tex]

3. [tex]K^++6H_2O\rightarrow K(H_2O)_6[/tex] Lewis acid : [tex]K^+[/tex], Lewis base : [tex]H_2O[/tex]

Explanation:

According to the Lewis concept, an acid is defined as a substance that accepts electron pairs and base is defined as a substance which donates electron pairs.

1. [tex]H^++OH^-\rightarrow H_2O[/tex]

As [tex]H^+[/tex] gained electrons to complete its octet. Thus it acts as lewis acid.[tex]OH^-[/tex] acts as lewis base as it donates lone pair of electrons to electron deficient specie [tex]H^+[/tex].

2. [tex]Cl^-+BCl_3\rightarrow BCl_4^-[/tex]

As [tex]BCl_3[/tex] is short of two electrons to complete its octet. Thus it acts as lewis acid. [tex]Cl^-[/tex] acts as lewis base as it donates lone pair of electrons to electron deficient specie [tex]BCl_3[/tex].

3. [tex]K^++6H_2O\rightarrow K(H_2O)_6[/tex]

As [tex]K^+[/tex] is short of electrons to complete its octet. Thus it acts as lewis acid. [tex]H_2O[/tex] acts as lewis base as it donates lone pair of electrons to electron deficient specie [tex]K^+[/tex].

Answer:I suppose it is mercury...

Explanation:

I don't say u must have to mark my ans as brainliest but if it has really helped u plz don't forget to thnk me...

Answer:

  1703 mmHg

Explanation:

Volume and pressure are presumed to be inversely proportional. Hence a change in volume by a factor of 125/325 = 5/13 is expected to change the pressure by a factor of 13/5:

  (13/5)(655 mmHg) = 1703 mmHg

Answer:

Lithium

Explanation:

The specific geat capacity of a substance is the energy required to raise 1 unit of that substance by one degree.

Heat energy (Q) = mc∇t

Q = heat energy

M = mass of the substance

c = specific heat capacity

∇t = change in temperature of the substance

Generally, increase in the specific heat capacity will lead to a lower final temperature likewise decrease in the specific heat capacity will lead to increase the final temperature of the substance.

From the data above, we can take just two specific heat capacity and test this theory.

Assuming we have a

Mass = 25g

Heat energy applied (Q) = 1 J

Initial temperature (T1) = 10°C

Final temperature (T2) = ?

Q = mc∇t

Q = mc (T2 - T1)

For Lithium, specific heat capacity = 3.58J/g°C

1 = 25 × 3.58 (T2 - 10)

Solve for T2

1 = 89.5 (T2 - 10)

1 = 89.5T2 - 895

89.5T2 = 896

T2 = 896 / 89.5

T2 = 10.011°C

For Magnesium (Mg) specific heat capacity = 1.02J/g°C

Q = mc∇t

1 = 25 × 1.02 × (T2 - 10)

1 = 25.5 (T2 - 10)

1 = 25.5T2 - 255

Solve for T2

25.5T2 = 256

T2 = 10.039°C

Notice the trend that decrease in the specific heat capacity leads to increase in the final temperature.

Try and continue for the elements and see how it works.

Answer:

Gold(III) chloride

Answer:

C) Steam condensing on a mirror

Explanation:

This was just a change in the physical state.

Answer:

here is ur and

Explanation:

Coal, oil and natural gas are called fossil fuels. Fossil fuels are burned to make energy. Burning fossil fuels also releases CO2 (carbon dioxide) gas into the atmosphere. Most air pollutants (such as sulfur dioxide) don't stay in the atmosphere very long.

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Answer:

D) it is the heat required to change a gram of substance from a liquid to a gas

Explanation:

idk i think its correct but if its wrong just let me know

Answer:

[tex]m=20kg[/tex]

Explanation:

Hello,

In this case, we define the kinnetic energy as:

[tex]K=\frac{1}{2} m*v^2[/tex]

Thus, for finding the mass we simply solve for it on the previous equation given the kinetic energy and the velocity:

[tex]m=\frac{2*K}{v^2}=\frac{500kg*\frac{m^2}{s^2} }{(5\frac{m}{s})^2} =\frac{500kg*\frac{m^2}{s^2} }{25\frac{m^2}{s^2}}\\\\m=20kg[/tex]

Best regards.

Answer:

The answer is 40 kg

Explanation:

You will this formula below:

m=[tex]\frac{2*\\KE}{v^{2} }[/tex]

Now we know our formula, now we plug in the given numbers:

m=[tex]\frac{2(500J)}{(5m/s)^2}[/tex]

Simplify and we get:

m=40 kg

I hope this was helpful.

42.1°C is the final temperature when a 25.0 g block of aluminum (initially at 25 °C) absorbs 10.0 kJ of heat.

The physical concept of temperature indicates in numerical form how hot or cold something is. A thermometer is used to determine temperature. Thermometers are calibrated using a variety of temperature scales, which historically defined distinct reference points or thermometric substances.

The most popular scales include the Celsius scale, sometimes known as centigrade, with the unit symbol °C, the scale of degrees Fahrenheit (°F), or the Kelvin scale (K), with the latter being mostly used for scientific purposes. One of the United Nations System of Units' (SI) seven base units is the kelvin.

Q=725 J

m=55.0 g

c=0.900 J/(°C⋅g)

ΔT=final temperature - initial temperature

ΔT=(x−27.5)°C

725 J=55.0 g⋅0.900 J/(°C⋅g)(x−27.5)

X=42.1°C

Therefore, 42.1°C is the final temperature when a 25.0 g block of aluminum (initially at 25 °C) absorbs 10.0 kJ of heat.

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Answer:

[Cd²⁺] = 2.459x10⁻⁶M

Kf = 9.96x10⁶

Explanation:

Solubility of CdC₂O₄ is 6.1x10⁻³M and ksp is 1.5x10⁻⁸

The ksp of CdC₂O₄ is:

CdC₂O₄(s) ⇄ Cd²⁺(aq) + C₂O₄²⁻(aq)

ksp = [Cd²⁺] [C₂O₄²⁻] = 1.5x10⁻⁸

As solubility is 6.1x10⁻³M, concentration of C₂O₄²⁻ ions is 6.1x10⁻³M. Replacing:

[Cd²⁺] = 1.5x10⁻⁸ / [6.1x10⁻³M]

All Cd²⁺ in solution is 6.1x10⁻³M and exist as Cd²⁺ and as Cd(NH₃)₄²⁺. That means concentration of Cd(NH₃)₄²⁺ is:

[Cd(NH₃)₄²⁺] + [Cd²⁺] = 6.1x10⁻³M

[Cd(NH₃)₄²⁺] = 6.1x10⁻³M - 2.459x10⁻⁶M = 6.098x10⁻³M

In the same way, the whole concentration of NH₃ in solution is 0.150M, as you have 4ₓ6.098x10⁻³M = 0.024M of NH₃ producing the complex, the concentration of the free NH₃ is:

[0.150M] = [NH₃] + 0.024M

The equilibrium of the complex formation is:

Cd²⁺ + 4 NH₃ → Cd(NH₃)₄²⁺

The kf, formation constant, is defined as:

Kf = [Cd(NH₃)₄²⁺] / [Cd²⁺] [NH₃]⁴

Replacing:

Kf = [6.098x10⁻³M] / [2.459x10⁻⁶M] [0.1256M]⁴

Answer:

0.3mL

Explanation:

Mass = 0.30mg

Concentration = 1.0 mg/mL

Volume = x

The relationship between the three parameters is given as;

Concentration = Mass / Volume

Making Volume our subject of interest we have;

Volume = Mass / Concentration

Substituting the values we have;

Volume = 0.30 mg / 1 mg/mL = 0.3mL

Answer:

Explanation:

From the question, osmotic pressure exerted by a solution is equal to the MOLARITY multiplied by the absolute TEMPERATURE and the GAS CONSTANT r.

Let P = osmotic pressure,

C = molarity, then

T = absolute temperature

r=gas constant

The Osmotic pressure Equation exerted by a solution [tex]P=C*T*r[/tex]

[tex]P=CTr[/tex]

Then it was required in the question to write an equation that will let you calculate the molarity c of this solution, and this equation should contain ONLY symbols

C= molarity of the solution

P=osmotic pressure

r = gas constant

T= absolute temperature

[tex]C=P/(rT)[/tex]

The equation that will let us calculate the molarity c of this solution = [tex]C=P/(rT)[/tex]

Answer:

We can produce 6.20 grams of CO2

Explanation:

Step 1: Data given

Mass of hexane = 4.3 grams

Molar mass of hexane = 86.18 g/mol

Mass of oxygen = 7.14 grams

Molar mass of oxygen = 32.0 g/mol

Step 2: The balanced equation

2C6H14 + 19O2 → 12CO2 + 14H2O

Step 3: Calculate moles

Moles = mass / molar mass

Moles hexane = 4.3 grams / 86.18 g/mol

Moles hexane = 0.0499 moles

Moles oxygen = 7.14 grams / 32.0 g/mol

Moles oxygen = 0.2231 moles

Step 4: Calculate the limiting reactant

For 2 moles hexane we need 19 moles O2 to produce 12 moles CO2 and 14 moles H2O

Oxygen is the limiting reactant. It will completely be consumed ( 0.2231 moles). Hexane is in excess. There will react 2/19 * 0.2231 = 0.02348 moles

There will be porduced 12/19 * 0.2231 = 0.1409 moles CO2

Step 5: Calculate mass CO2

Mass CO2 = moles CO2 * molar mass CO2

Mass CO2 = 0.1409 moles * 44.01 g/mol

Mass CO2 = 6.20 grams

We can produce 6.20 grams of CO2

Answer:

[Z] = 0.00248M

Explanation:

Based in the reaction:

2A(aq) + B(aq) ⇄ 2Z (aq)

K of the reaction is defined as:

K = [Z]² / [A]²[B] = 0.43

If you add, in the first, just 0.033M of  Z, concentrations in equilibrium are:

[Z] = 0.033M - 2X

[A] = 2X

[B] = X

Replacing in K equation:

0.43 = [0.033M - 2X]² / [2X]² [X]

0.43 = [0.033M - 2X]² / [2X]² [X]

0.43 = 4X² -0.132X + 0.001089 / 4X³

1.72X³ - 4X² + 0.132X - 0.001089 = 0

Solving for X:

X = 0.01526M

Replacing, concentration in equilibrium of Z is:

[Z] = 0.033M - 2*0.01526M = 0.00248M

Answer:

Less than 0.033 M

Explanation:

Hello,

In this case, given the equilibrium:

[tex]2A(aq) + B(aq) \rightleftharpoons 2Z (aq)[/tex]

Thus, the law of mass action is:

[tex]K=\frac{[Z]^2}{[A]^2[B]}[/tex]

Nevertheless, given the initial concentration of Z that is 0.033 M, we should invert the equilibrium since the reaction will move leftwards:

[tex]\frac{1}{K} =\frac{[A]^2[B]}{[Z]^2}=2.33[/tex]

Know, by introducing the change  due to the reaction extent, we can write:

[tex]2.33=\frac{(2x)^2*x}{(0.033M-2x)^2}[/tex]

Which has the following solution:

[tex]x_1=2.29M\\x_2=0.0181M\\x_3= 0.0153M[/tex]

But the correct solution is [tex]x=0.0153M[/tex]  since the other solutions make the equilibrium concentration of Z negative which is not possible. In such a way, its concentration at equilibrium is:

[tex][Z]_{eq}=0.033M-2*0.0153M=0.0024M[/tex]

Which is of course less than 0.033 M since the addition of a product shift the reaction leftwards in order to reestablish equilibrium (Le Chatelier's principle).

Regards.

Complete Question

A chemistry student weighs out 0.950 kg  of an unknown solid compound and adds it to 2.00 L of distilled water at . After minutes of stirring, only some of the has dissolved. The student drains off the solution, then washes, dries and weighs the that did not dissolve. It weighs 0.570 kg.

Required:

a. Using the information above, can you calculate the solubility of X?

b. If so, calculate it. Remember to use the correct significant digits and units. .

Answer:

a

Yes the solubility of X can be calculated this is because the solubility of a substance dissolved in a solution is the amount of that substance that is needed to saturate  1 unit volume of the solvent solution at that given temperature.

And from our question we see that substance  X saturated the solvent and there is  still remained undissolved substance X

b

The solubility of X is  [tex]S = 190 g /L[/tex]

Explanation:

From the question we are told that

    The initial mass of the unknown solid is [tex]m_i =0. 950 \ kg[/tex]

    The mass of the undissolved substance is  [tex]m_u = 0.570 \ kg[/tex]

    The volume of the solution is  [tex]V =2.00\ L[/tex]

Yes the solubility of X can be calculated this is because the solubility of a substance dissolved in a solution is the amount of that substance that is needed to saturate  1 unit volume of the solvent solution at that given temperature.

And from our question we see that substance  X saturated the solvent and there is  still remained undissolved substance X

The mass of the substance that dissolved ([tex]m_d[/tex] ) is mathematically represented as

    [tex]m_d = m_i - m_u[/tex]

  [tex]m_d = 0.95 - 0.570[/tex]

    [tex]m_d = 0.38 \ kg = 0.38 *1000 = 380 g[/tex]

The solubility of this substance (X) is mathematically represented as

      [tex]S = \frac{m_d}{V}[/tex]

substituting values

     [tex]S = \frac{ 380}{2}[/tex]

     [tex]S = 190 g /L[/tex]

Answer:

D

Explanation:

trust me its correct i think

Answer:

Hi there!

When dropping Alka-Seltzer into a glass of water, bubbles immediately appear and the solid substance “disappears”, dissolves, into the water. This forms a new compound, a liquid, which means a reaction took place.

Answer:

\large \boxed{\text{2.0 atm}}  

Explanation:

We can use Dalton's Law of Partial Pressures:

Each gas in a mixture of gases exerts its pressure separately from the other gases.

0.25 mol of O₂ exerts 0.50 atm.

If you add 0.75 mol of CO, the total amount of gas is  

0.25 mol + 0.75 mol = 1.00 mol

[tex]p_{\text{total}} = \text{1.00 mol} \times \dfrac{\text{0.50 atm}}{\text{0.25 mol}}= \textbf{2.0 atm}\\\\\text{The total pressure in the flask is $\large \boxed{\textbf{2.0 atm}}$}[/tex]

The pressure of the closed flask after the addition of 0.75 moles of CO has been 2 atm.

Partial pressure can be defined as the pressure exerted by each gas in a given solution.

The total moles of gas in the container by the addition of CO has been:

Total moles = moles of oxygen + moles of CO

Total moles = 0.25 + 0.75

Total moles = 1 mol.

By using Dalton's law of partial pressure:

Total pressure = total moles [tex]\rm \times\;\dfrac{pressure\;of\;oxygen}{moles\;of\;oxygen}[/tex]

Total pressure = 1 [tex]\rm \times\;\dfrac{0.50}{0.25}[/tex]

Total pressure = 2 atm.

The pressure of the closed flask after the addition of 0.75 moles of CO has been 2 atm.

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Answer: From your question,

One could be exothermic which means that the final enthalpy will be less than the initial enthalpy. H= Hf-Hi(Hf<Hi).

In Endothermic reaction, the entropy is lowered by absorbing energy in the surronding. By so doing, the surronding losses energy and the reaction is not spontaneous.

H is positive and S (entropy) is positive.

Explanation:

Exothermic reaction is the reaction where heat is released In the surronding which lead to increase in the surronding Temperature.

Endothermic reaction is the reaction that absorb heat from the surronding and decrease the surronding Temperature.

Answer: light reaction produces oxygen and water as we know the general importance of oxygen and water they are useful for organism to survive if plants do not produce oxygen then how could we get oxygen from the environment

Answer:

D

Explanation:

Logitudinal waves also known as compression waves.

It involves displacing the medium perpendicular to the motion of the wave is not a characteristic of a transverse mechanical wave. Option B is correct.

A transverse mechanical wave is a disturbance created by it to transfer energy from one point to another. while the proposition happens the particle present within the medium get vibrates.

in a transverse wave, the particle present will vibrate up and down and are perpendicular to the wave's propagation direction. The particles shake in a directional wave in the longitudinal wave propagation.

Therefore, is not a characteristic of a transverse mechanical wave. Option B is correct. It involves displacing the medium perpendicular to the motion of the wave.

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Answer:

Decantation by means of difference in relative densities.

Explanation:

The specific gravity (relative density) of the gold to the soil/sand is the physical property exploited in panning gold. The particles with lower density would float whilst the heavier gold sinks lower to the bottom of the pan by gravity and is decanted off.

I hope this explanation is easy to comprehend.

Answer:

Anode half reaction;

Co(s) ----> Co^2+(aq) + 2e

Cathode half reaction;

2Ag^+(aq) + 2e-------> 2Ag(s)

Explanation:

A voltaic cell is an electrochemical cell that spontaneously produces electrical energy from chemical reactions. A voltaic cell comprises of an anode (where oxidation occurs) and a cathode (where reduction occurs). The both electrodes are connected with a wire . A salt bridge ensures charge neutrality in the anode and cathode compartments. Electrons flow from anode to cathode.

For the cell referred to in the question;

Anode half reaction;

Co(s) ----> Co^2+(aq) + 2e

Cathode half reaction;

2Ag^+(aq) + 2e-------> 2Ag(s)

Answer:

5-methylhex-1-yne//5-methylhex-2-yne//2-methylhex-3-yne

Explanation:

We have to start with the information on the IR spectrum. The signal at 3300 is due to a C-H bend sp carbon and the signal in 2200 is due to the stretch carbon-carbon. Therefore we will have an alkyne. Now if we have 2-methylhexane as the product of hydrogenation we have several options to put the triple bond. Between carbons 1 and 2 (5-methylhex-1-yne), between carbons 2 and 3 (5-methylhex-2-yne) and between carbons 3 and 4 (2-methylhex-3-yne). On carbon 5 we have a tertiary carbon therefore we dont have any other options.

See figure 1

I hope it helps!

Answer: The digestive system breaks down food into nutrients that are transported by the circulatory system.

Explanation:

An organ system includes the organs which are linked to one another to perform a physiological function in the body of the organism. The digestion is a complex process in which the food is being broken down into sub-components so that it can be assimilated in the body. The digestive system involves the multiple organs like mouth, esophagus, stomach, intestines and others. The food being digested is absorbed in the bloodstream, which circulate in the vital organs of the body like lungs, heart, vascular system hence, the blood becomes the part of the circulatory system.

Thus it can be said that the argument of children that the two systems are related is justified by the digestive and circulatory system of the body.

The given question is incomplete. The image present in the question for Reaction A is attached below along with the answer.

Explanation:

Pyruvate molecule reacts with Coenzyme A in the presence of oxygen and it results in the formation of acetyl Coenzyme A and carbon dioxide.

The enzyme pyruvae dehydrogenase helps in catalyzing this reaction. As in this biochemical reaction [tex]NAD^{+}[/tex] gets converted into NADH.

This reaction is shown in the image attached below.  

Answer:

3. Oxidation-Reduction Reaction

Explanation:

Fe(s) + Cl2(aq) = Fe2+(aq) + Cl-(aq)

Fe(s) -2e- ----> Fe2+(aq)  oxidation

Cl2(aq)  + 2e- -----> 2Cl-(aq)  reduction

The given unbalanced chemical reaction is the oxidation-reduction reaction. Therefore, option (3) is correct.

Redox reactions can be defined as oxidation-reduction chemical reactions in which the reactants of the reaction undergo a change in their oxidation states. All the redox reactions are further broken down into two different processes: a reduction process and an oxidation process.

The oxidation and reduction reactions take place simultaneously in an Oxidation-Reduction reaction. The substance that is getting reduced in a reaction is known as the oxidizing agent, while a substance that is getting oxidized is the reducing agent.

The given chemical reaction is:

[tex]Fe(s) + Cl_2(aq) \longrightarrow Fe^{2+}(aq) + Cl^-(aq)[/tex]

The oxidation reaction for this reaction is: Fe (s)  →  Fe²⁺ (aq)  + 2e⁻

The reduction reaction:  Cl₂ (g)  +  2e⁻   →  2Cl⁻ (aq)

Therefore, the given reaction between the iron and chlorine gas is the oxidation-reduction reaction or redox reaction.

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