Thallium-201 is a radioactive isotope that undergoes first-order decay. When the concentration of 201Tl is 0.0042 M, its half-life is 73.0 hours. What is the half-life of 201Tl when its concentration is 0.0136 M?(A) 51.0 hours(B) 73.0 hours(C) 123 hours(D) 236 hours

The law is Boyel's law.

One of the primary laws of material science that impacts the submerged jumping condition for scuba jumpers is Boyle's law.  

The law states that as weight changes, the volume of gases in a jumper's body pits and adaptable gear changes as well. Where the water weight builds, 'air spaces' reduces in size, yet as water weight diminishes, the 'air spaces' increments in size. Where the two changes are in direct extent to the weight increment or lessening, the temperature is held consistent.  

A potassium atom loses one electron to form a potassium ion with a +1 charge, while a sulfur atom gains two electrons to form a sulfide ion with a -2 charge.

Metals and nonmetals can react with each other to form ions through the transfer of electrons. When a potassium atom reacts, it loses one electron and forms a potassium ion with a +1 charge (K+). Potassium is an alkali metal and it typically loses one electron to achieve a noble gas electron configuration.

On the other hand, a sulfur atom typically gains two electrons to form a sulfide ion with a -2 charge (S2-). As a nonmetal, sulfur gains electrons to achieve an octet, resembling the electron configuration of a noble gas.

Answer:

D. Earth's internal heat engine and the water cycle

Explanation:

The rock cycle is driven by the earth's internal heat engine and the water cycle.

The internal heat engine furnishes the earth with the required energy. The energy is used to melt rocks within the earth crust and to initiate convective cells in the mantle. This causes rocks to melt and plates to move. As this occurs, igneous and metamorphic processes takes place.

The water cycle is greatly responsible for the weathering and erosion of rocks. Through these processes of denudation, sediments are formed and deposited within basins on the crust. The action of runing water and glacier plays a very significant role in forming sedimentary rocks.

The interplay between the internal heat Engine and water cycle moves crustal materials to deeper levels of the earth and also deep seated materials to the crust.

The two forces that primarily drive the rock cycle are Earth's internal heat engine and the water cycle. Therefore, option D is correct.

The Earth's internal heat engine, which includes processes like volcanic activity, tectonic plate movements, and mountain building plays a crucial role in the rock cycle.

These processes generate heat and pressure that lead to the formation of new rocks through processes such as solidification, crystallization, and metamorphism.

The water cycle, driven by solar energy, also plays a role as it contributes to weathering and erosion by causing precipitation, runoff, and the movement of water through different stages.

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Answer:

Explanation:

The boiling point of a pure solven increases when a solute is added and a solution is formed.

The increase of the boiling point of a solvent, when a non-volatile solute is added, is a colligative property, meaning that it depends of the number particles of solute dissolved.

The equation that rules the increase of the boiling point is:

Where:

Then, since Kb is constant (because it is the same solvent for all the solutions), you must look at the product m × i.

For ionic solutes you assume 100% ionization, which drives to:

Solution                  Ionization           i        m         m × i

A) 2.0 BaCl₂             Ba⁺² + 2Cl⁻       3      2.0        6.0     ↔ highest

B) 2.0 NaNO₃          Na⁺ + NO₃⁻       2      2.0        4.0      ↔ second

C) 1.0 C₆H₁₂O₆          none                1       1.0         1.0      ↔ lowest (fourth)

D) 1.0 K₂SO₃             2K⁺ + SO₃²⁻      3      1.0         3.0     ↔ third

Then, 6.0 > 4.0 > 3.0 > 1.0 and the final list of the solutions arranged in order from highest boiling point to lowest boiling point is:

Answer:

The order should be ABDC.

Explanation:

Answer:

a) 5

b) 4

c) 3

d) 3

e) 4

Explanation:

I use only one rule when the decimal is present, meaning you can see the decimal (as is the case with all of these).

When the decimal is Present, start counting sig figs from the Pacific (left) side of the number beginning with the first non-zero digit and count all the way to the end.

So, for example, in "a", the first non-zero digit starting from the left is 1, then continue counting all the way to the right side.

For "c",  the first non-zero digit is the left most 4 (skip the first 4 zeros), then count all the way to the right side.

Answer:

4.549 kg.

Explanation:

where, P is the pressure of the gas in atm (P = 2 x 10⁴ kPa/101.325 = 197.4 atm).

V is the volume of the gas in L (V = 20.0 L).

n is the no. of moles of the gas in mol (n = ??? mol).

R is the general gas constant (R = 0.0821 L.atm/mol.K),

T is the temperature of the gas in K (T = 23° C + 273 = 296 K).

∴ n = PV/RT = (197.4 atm)(20.0 L)/(0.0821 L.atm/mol.K)(296 K) = 162.5 mol.

mass of N₂ = (no. of moles of N₂)*(molar mass of N₂) = (162.5 mol)*(28.0 g/mol) = 4549 g = 4.549 kg.

Answer:

The new volume of the balloon is 600cm³

Explanation:

Given parameters:

Initial Volume, which is V₁ = 200cm³

Initial temperature, T₁ = 60°C

Final temperature T₂ = 180°C

Final Volume V₂ =?

To solve this kind of problem, we apply one of the gas laws that shows the relationship between volume and temperature.

This law is the Charles law, it states that " the volume of a fixed mass of a gas is directly proportional to its absolute temperature if pressure is constant".

It is simply expressed as:

V₁/T₁ = V₂/T₂

Since our unknown is V₂, we make it the subject of the expression given above:

V₂ = V₁T₂/T₁

Now input the corresponding values and solve:

V₂ = 200 x 180 / 60

V₂ = 36000/60

V₂ = 600cm³

The new volume of the balloon is 600cm³

The answer is d ionic

Answer:

Explanation:

That's almost the exact definition of an ecosystem.

Hello!

I think an ecosystem because they are a biological community of interacting organisms and their physical environment. And that’s what an ecosystem is and it relates to your question.

I hope I answered in time!

Good luck!

~ Destiny ^_^

Answer:

Explanation:

Boyle's law for gases states that, at constant temperature, the volume and pressure of a fixed amount of gas are inversely related.

Mathematically, that is:

Here, you have:

Then, you can solve for V₂:

Substitute and compute:

Answer:

0.40 L

Explanation:

Answer:

The weak nuclear force.

Explanation:

This force is active in radioactivity.

Answer:

Explanation:

The angular momentum quantum number, identified with the letter l (lowercase L),  number is the second quantum number.

This number identifies the shape of the orbital or kind of subshell.

The possible values of the angular momentum quantum number, l, are constrained by the value of the principal quantum number n: l can take values from 0 to n - 1.

So, you can use this guide:

Principal quantum   Angular momentum         Shape of the orbital

number, n                 quantum number, l

         1                                      0                             s

         2                                     0, 1                          s, p

         3                                     0, 1, 2                      s, p, d

Hence,

To calculate the amount of heat energy added to the water, multiply the mass of water by the specific heat of water and the change in temperature.

To calculate the amount of heat energy added to the water, we can use the equation:

q = m * c * ΔT

Where q is the heat energy, m is the mass of the water (2 grams), c is the specific heat of water (4.184 J/g °C), and ΔT is the change in temperature (final temperature minus initial temperature).

Substituting the values into the equation, we get:

q = 2g * 4.184 J/g°C * (50°C - 40°C)

q = 2g * 4.184 J/g°C * 10°C

q = 83.68 J

Therefore, 83.68 Joules of heat energy is added to 2 grams of water.

Answer:it speeds up the reaction

Explanation:

Answer:

The catalyst is unchanged.

Explanation:

Hope my answer has helped you!

Answer: I believe the Answer is A

Answer:

a substance whose nuclei do not stay together

Explanation:

Answer:

0.6 mol/L.s.

Explanation:

3O₂ → 2O₃,

the rate of the reaction = - 1/3d[O₂]/dt = 1/2d[O₃]/dt

where, d[O₂]/dt is the rate of change of O₂ concentation = - 0.9 mol/L.s.

d[O₃]/dt is the rate of change of O₃ concentration.

∴ d[O₃]/dt = - 2/3(d[O₂]/dt) = - 2/3(- 0.9 mol/L.s) = 0.6 mol/L.s.

Answer:

True

Explanation:

as the ph of pure water is 7

(-)log(10^-7) = 7

The statement if the pH of pure water is 7.0, the hydroxide ion concentration in pure water is 1 × 10⁻⁷M is true.

Hydroxide ion concentration in the solution will be calculated by using the below equation as:

pOH = -log[OH⁻]

Relation between pH and pOH is :

pH + pOH = 14

Given that, pH = 7

So, pOH = 14 - 7 = 7

By using first equation, we have

7 = -log[OH⁻]

[OH⁻] = 10⁻⁷M

Hence, hydroxide ion concentration in pure water is 1×10⁻⁷M.

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The answer is excess reactant

Answer: option B, excess reactant

Explanation:

Since one the reactants is in excess(high amount) compared to other.

Example reaction of H2& Cl2 gives HCl.

If we take excess H2 compared to Cl2. Then we call H2 as excess Reactant.

Answer:

D. Temperature

Explanation:

Temperature is not energy, let's just make that point first. So how can it be the average kinetic energy then?

Well, the short answer is, it is just a number. Temperature is a number that represents the average kinetic energy. It is important to note that temperature only relates to kinetic energy in substances.

This is what makes it different from heat. Heat considers all forms of energy in the substance.

Answer:

TEMPERATUE

Explanation:

Answer: metal and carbonate

Explanation:

According to Arrhenius concept, a base is defined as a substance which donates hydroxide ions [tex](OH^-)[/tex] when dissolved in water and an acid is defined as a substance which donates hydrogen ions [tex](H^+)[/tex] in water.

An acid is represented as :

[tex]HX\rightarrow H^++X^-[/tex]

1. When metal is treated with an acid such as [tex]HCl[/tex], if the metal is more reactive than hydrogen displaces hydrogen from its salt solution and thus produce zinc chloride and hydrogen gas.

[tex]M+xHCl(aq)\rightarrow MCl_x(aq)+xH_2(g)[/tex]

2. When carbonates are treated with acid, double displacement takes place ad carbon dioxide is released as a gas.

[tex]MCO_3(aq)+xHCl(aq)\rightarrow MCl_x(aq)+xH_2O(l)+CO_2(g)[/tex]

Answer:

for those in a hurry, its C

Explanation:

on edge. Metal and carbonates

Answer:

A. Yes, Amanda find the number of moles of NaCl correctly.

B. 0.73 M.

Explanation:

A. Did Amanda find the number of moles of NaCl correctly? If not, explain.

No. of moles (n) of NaCl = mass/molar mass.

mass of NaCl = 32.0 g, molar mass of NaCl = 58.45 g/mol.

∴ No. of moles (n) of NaCl = mass/molar mass = (32.0 g)/(58.45 g/mol) = (32.0 g NaCl)*(1 mol of NaCl)/(58.45 g NaCl) = 0.547 mol ≅ 0.55 mol.

B. What does Amanda need to do next to calculate the molarity of the NaCl solution? Show your work for full credit.

∴ M = (no. of moles of NaCl)/(volume of solution (L)) = (0.55 mol)/(0.75 L) = 0.73 M.

They are gases at room temperature

Hope this helps:)

The smallest alkanes, which are those with one to four carbon atoms, are gases at room temperature due to their nonpolar nature and weak dispersion forces.

The physical state of the smallest alkanes at room temperature can be understood by analyzing their properties and boiling points. Alkanes are nonpolar molecules associated through weak dispersion forces. The boiling point of a substance is a rough measure of the energy needed to separate molecules from each other. In the case of the smallest alkanes, specifically those with one to four carbon atoms, they are gases at room temperature. Example alkanes that are gases at room temperature include methane (CH4), ethane (C2H6), propane (C3H8), and butane (C4H10). In contrast, the physical state changes as the number of carbons increases; alkanes become liquids and eventually solids as the carbon chain length and molecular weight increase.

These are five questions and five answers.

1) Question 1. A sample of pure calcium fluoride with a mass of 15.0 g contains 7.70 g of calcium. How much calcium is contained in 40.0 g of calcium fluoride?

Answer:

Explanation:

Calcium fluoride being a pure substance, has a fixed chemical compositon, which means that their elements (atoms), in any sample, are always in the same proportion.

Then, you can set the followoing proportion:

Now, solve for x:

The answer must be expressed with 3 significan figures, since the three data are given with 3 significan figures.

2) Question 2. Silver has two isotopes. One isotope contains 60 neutrons and has a percent abundance of 51.839% the other contains 62 neutrons. Give the atomic symbols for the two isotopes.

Answer:

Explanation:

         Isotope that contains 60 neutrons: A = 60 + 47 = 107

         Isotope that contains 62 neutrons: A = 62 + 47 = 109

         Isotope with 60 neutrons: ¹⁰⁷₄₇Ag

         Isotope with 62 neutrons:  ¹⁰⁹₄₇Ag

3) Question 3. What is the average atomic weight of silver? What is the mass (in grams) of a single chlorine molecule?

Answer:

Explanation:

The atomic wieght of the elements is the weighted average weight of the different isotopes of the same element found in the nature,  taking into account their relative abundance.

Average atomic weight = ∑( abundance × individual atomic weight)

4) Question without number: What is the mass (in grams) of a single chlorine molecule

Answer:

Explanation:

The chlorine molecule is diatomic. That means that each molecule contains two atoms. The chemical formula of chlorine molecule is Cl₂.

The mass of one mole of molecules of Cl₂ is 2 × 35.453 g/mol = 70.906 g/mol

5) Question 4. How many moles of ethanol (CH₃CH₂OH) are in 141 mg?

Answer:

Explanation:

In 40.0 g of calcium fluoride, there is 20.53 g of calcium. Silver has two isotopes represented by Ag-107 and Ag-109, with the average atomic weight of silver calculated by using their percent abundances. For ethanol, 141 mg corresponds to 0.00306 moles.

Calcium is contained in 40.0 g of calcium fluoride (CaF₂), we use a proportional relationship based on the information provided:

15.0 g of CaF₂ contains 7.70 g of calcium.

40.0 g of CaF₂ contains X g of calcium.

By setting up a proportion, we solve for X:

(7.70 g Ca / 15.0 g CaF₂) = (X g Ca / 40.0 g CaF₂)X = (7.70 g Ca / 15.0 g CaF₂)
40.0 g CaF₂)

X = 20.53 g of calcium.

The atomic symbols for the two isotopes of silver are: Ag-107 (47 protons + 60 neutrons) and Ag-109 (47 protons + 62 neutrons).

The average atomic weight of silver is calculated considering the weighted average of these isotopes and their percent abundances. The mass of a single chlorine molecule (Cl₂), not a chlorine atom, would be the sum of the atomic masses of the two chlorine atoms. However, the specific mass for a single molecule of Cl₂ in grams is a very small number, given that it's typically calculated in atomic mass units.

Finding the number of moles of ethanol (CH₃CH₂OH) in 141 mg:

The molar mass of ethanol is approximately 46.07 g/mol. Therefore:(141 mg) (Unit conversion from mg to g: 141 mg * (1 g/ 1000 mg)) (Divide by the molar mass of ethanol: (0.141 g) / 46.07 g/mol) = 0.00306 mol of ethanol.

Answer:

[tex]\boxed{\text{0.60 L}}[/tex]

Explanation:

We can use Gay-Lussac's Law of Combining Volumes to solve this problem.

Gases at the same temperature and pressure react in the same ratios as their coefficients in the balanced equation.

1. Write the chemical equation.

Ratio: 2 L     1 L

           2H₂ + O₂ → 2H₂O

V/L:   1.2

2. Calculate the volume of O₂.

According to Gay-Lussac, 1 L of O₂ forms from 2 L of H₂.

Then, the conversion factor is (1 L O₂/2 L H₂).

[tex]\text{Volume of O}_{2} = \text{1.20 L H}_{2}\times \dfrac{\text{1 L O}_{2}}{\text{2 L H}_{2}} = \textbf{0.60 L O}_{2}\\\\\text{You need }\boxed{\textbf{0.60 L of O}_{2}}[/tex]

Answer:

404 J

Explanation:

The amount of heat given off by the magnesium sample is given by:

[tex]Q=mC_s \Delta T[/tex]

where

m = 20.0 g is the mass of the sample

[tex]C_s = 1.01 J/gC[/tex] is the specific heat capacity of the magnesium

[tex]\Delta T=50.0 C-70.0 C=-20.0^{\circ}[/tex] is the change in temperature

Substituting into the equation, we find

[tex]Q=(20.0 g)(1.01 J/gC)(-20.0^{\circ})=-404 J[/tex]

and the negative sign means the heat is given off by the sample.

Using the formula for heat exchange (q = mcΔT), we find that a 20.0 gram sample of magnesium releases 404 Joules of heat when cooling from 70.0°C to 50.0°C

The student's question involves the physics concept of specific heat. Specific heat is the heat required to change the temperature of 1 gram of a substance by 1 degree Celsius, it's an intensive property. To calculate the amount of heat given off you can use this formula: q = mcΔT, where:

For the given problem, the mass (m) of magnesium is 20.0 grams, its specific heat (c) is 1.01 J/g°C and the change in temperature (ΔT) is 70.0°C - 50.0°C = 20.0°C. So,

q = mcΔT

= (20.0 g) * (1.01 J/g°C) * (20.0°C)

= 404 J

Therefore, 404 Joules of heat is released when the 20.0 gram sample of magnesium cools from 70.0°C to 50.0°C.

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Answer : The correct option is, Add coefficient 2 to [tex]O_2[/tex] on the left side of the equation.

Explanation :

Balanced chemical reaction : It is defined as the reaction in which the number of atoms of individual elements present on reactant side must be equal to the product side.

The reactants and the products are separated by right arrow.

The species present on the left side of the right arrow is known as reactant and the species present on the right side of the right arrow is known as product.

If the amount of atoms of each type on the left and right sides of a reaction differs then to balance the equation by adding coefficient in the front of the elements or molecule or compound in the chemical equation.

The coefficient tell us about that how many molecules or atoms present in the chemical equation.

The given chemical reaction is,

[tex]CH_4+O_2\rightarrow CO_2+2H_2O[/tex]

This reaction is an unbalanced chemical reaction because in this reaction number of oxygen atoms are not balanced.

In order to balance the chemical equation, the coefficient '2' put before the [tex]O_2[/tex] and we get the balanced chemical equation.

The balanced chemical reaction will be,

[tex]CH_4+2O_2\rightarrow CO_2+2H_2O[/tex]

Hence, the correct option is, Add coefficient 2 to [tex]O_2[/tex] on the left side of the equation.

Answer:

(Percent yield × theoretical yield) ÷ 100.

Explanation:

∵ percent yield of the reaction = [(actual yield)/(theoretical yield)] x 100.

∴ actual yield = [(percent yield of the reaction) x (theoretical yield)]/100.

So the right choice is: (Percent yield × theoretical yield) ÷ 100 .

Answer : The correct option is, [tex]\frac{(\text{Percent yield}\times \text{Theoretical yield})}{100}[/tex]

Explanation :

The formula used for the percent yield will be :

[tex]\text{Percent yield}=\frac{\text{Actual yield}}{\text{Theoretical yield}}\times 100[/tex]

or,

[tex]\text{Actual yield}=\frac{(\text{Percent yield}\times \text{Theoretical yield})}{100}[/tex]

For example : If we are given that the percentage yield of a sample is 94.92% and the theoretical yield is 83.475 g. Now calculate the actual yield of the sample.

By using formula we get the value of actual yield.

[tex]\text{Actual yield}=\frac{(94.92\times 83.475)}{100}=79.23g[/tex]

Thus, the actual yield is, 79.23 g.

Hence, the formula used to calculate the actual yield can be, [tex]\frac{(\text{Percent yield}\times \text{Theoretical yield})}{100}[/tex]

Answer:

heat is relaesed

a decrease in temperature

less than the chemical energy

written as a reactant

Explanation:

Answer:

Answer is Below

Explanation:

For an exothermic reaction, heat is released. Which means that...

1. Heat is written as a product of the reaction.

2. A rise in temperature occurs.

3. Heat is released into the surroundings.

and 4. The chemical energy stored in the bonds of the products is less than that stored in the reactants.

This diagram also explains why this is the case, the chemical energy is lower as you see the products is lower on the graph as compared to the reactants.

A on nudity

Reason: ye