Radium has a half-life of 1500 years. How long will it take for 250kg of Radium to decay down to less than 10kg

Answer:

44.8g

Explanation:

molar mass of k= 39, O= 16, H= 1

molecular mass of KOH= 56g/mol

N=m/Mm

0.8=m/56

m= 0.8×56

m= 44.8g

Mass is "a measure of the amount of matter that an object contains".

Matter is "any substance that has mass and takes up space by having volume".

The formula to calculate the molar mass is M = m/n

where M is molar mass

           m is mass of substance in grams

           n is no. of moles of a substance.

The molecular mass of KOH is 56.105 g/mol

molar mass of K= 39, O= 16, H= 1

M = m/n

 0.8 = m/56.105

    m = 0.8 x 56.105

     m  = 44.8g

Hence, the mass of 0.8 mol of KOH is 44.8g

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Answer:

Explanation:

Given the data in the question;

wavelength λ₁ = 853 nm = 853 × 10⁻⁹ m

wavelength λ₂ = 865 nm = 865 × 10⁻⁹ m

we determine the energy of each photons using the following expression;

[tex]E_{photon[/tex] = hc / λ

where h is Planck's constant ( 6.626 × 10⁻³⁴ J.s )

c is speed of light ( 3 × 10⁸ m/s )

For Photon with wavelength λ₁ = 853 × 10⁻⁹ m

[tex]E_{photon1[/tex] = hc / λ

we substitute

= ( ( 6.626 × 10⁻³⁴ J.s )( 3 × 10⁸ m/s ) ) / (853 × 10⁻⁹ m)

= 1.9878 × 10⁻²⁵ / 853 × 10⁻⁹

= 2.33 × 10⁻¹⁹ J

For Photon with wavelength  λ₂ = 865 × 10⁻⁹ m

[tex]E_{photon2[/tex] = ( ( 6.626 × 10⁻³⁴ J.s )( 3 × 10⁸ m/s ) ) / (865 × 10⁻⁹ m)

= 1.9878 × 10⁻²⁵ / 865 × 10⁻⁹

= 2.298 × 10⁻¹⁹ J

We know that; energy of the combined photon will be equal to the sum of energies of the two photons.

so

Energy of the combined photon = [tex]E_{photon1[/tex] + [tex]E_{photon2[/tex]

[tex]E_{combined[/tex] = 2.33 × 10⁻¹⁹ J + 2.298 × 10⁻¹⁹ J

[tex]E_{combined[/tex]  = 4.628 × 10⁻¹⁹ J

so wavelength of the new combined photon will be;

[tex]E_{combined[/tex] = hc / λ[tex]_{combined[/tex]

[tex]E_{combined[/tex]λ[tex]_{combined[/tex] = hc

λ[tex]_{combined[/tex] = hc / [tex]E_{combined[/tex]

we substitute

λ[tex]_{combined[/tex] = ( ( 6.626 × 10⁻³⁴ J.s )( 3 × 10⁸ m/s ) ) / 4.628 × 10⁻¹⁹ J

= 1.9878 × 10⁻²⁵ / 4.628 × 10⁻¹⁹

= 4.2952 × 10⁻⁷ m

= ( 4.2952 × 10⁻⁷ × 10⁹ )nm

= 429.5 nm

Therefore, Wavelength of the new 'combined' photon is 429.5 nm

Answer:

It can be said that a reasonable concentration of HAt in water would be 0

Explanation:Hydrogen astatide is a chemical compound with the chemical formula HAt, consisting of an astatine atom covalently bonded to a hydrogen atom.

This chemical compound can dissolve in water to form hydroastatic acid, which exhibits properties very similar to the other four binary acids, and is in fact the strongest among them. So we can safely say that a reasonable concentration of HAt in water would be 0. However, it is limited in use due to its ready decomposition into elemental hydrogen and astatine.

Answer:Gamma radiation is the product of radioactive atoms. Depending upon the ratio of neutrons to protons within its nucleus, an isotope of a particular element may be stable or unstable.

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Answer:

4.42 x 10^24

Explanation:

Answer:

8

Explanation: # of protons = atomic #

Answer:

NaOH is the limiting reactant.

Explanation:

Hello there!

In this case, according to the given information, it turns out firstly necessary to write out the chemical reaction between NaOH and HCl:

[tex]NaOH+HCl\rightarrow NaCl+H_2O[/tex]

Thus, since they react in a 1:1 mole ratio; we can now calculate the moles of each substance by using their volumes and molarities:

[tex]n_{NaOH}=0.0250L*0.81mol/L=0.02025molNaOH\\\\n_{HCl}=0.0650L*0.33mol/L=0.02145molHCl[/tex]

Now, since NaOH is in a fewer proportion, we infer just 0.02025 moles of HCl are consumed so that 0.0012 moles of this acid remain unreacted; in such a way, we infer that the NaOH is the limiting reactant for this reaction.

Regards!

The wavelength of the light having a frequency of 7.21×10¹⁴ Hz is 416 nm (Option C)

Wavelength and frequency are related to the velocity of a wave according to the following formula:

Velocity (v) = wavelength (λ) × frequency (f)

v = λf

With the above formula, the wavelength of the light can be obatined. Details below.

From the question given above, the following data were obtained:

Velocity (v) = wavelength (λ) × frequency (f)

3×10⁸ = wavelength × 7.21×10¹⁴

Divide both sides by 7.21×10¹⁴

Wavelength = 3×10⁸ / 7.21×10¹⁴

Wavelength = 416×10⁻⁹ m

Multiply by 10⁹ to express in nm

Wavelength = 416×10⁻⁹ × 10⁹

Wavelength = 416 nm

Thus, we can conclude that the wavelength is 416 nm (Option C)

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Answer:

The empirical formula of the chemical compound is C₆H₁₂SO₂

Explanation:

To determine the empirical formula, the mass of each element in the compound is first determined from their respective compounds formed after combustion analysis.

Mass of element = mass of compound × molar mass of element / molar mass of compound

Carbon: 53.694 g x (12g/mol / 44.0 g/mol) = 14.643 mg of C in 30.141 mg sample Hydrogen: 21.980 mg x ( 2.00 / 18.00) = 2.442 mg of H in 30.141 mg sample

Sulfur: 13.05 mg x (32.00/ 64.00) = 6.525 mg of S in 30.199 mg in sample

The percentage mass composition of the elements in the compound is then determined:

Carbon: 14.643 mg / 30.141 mg = 48.58%

Hydrogen: 2.442 mg / 30.141 mg = 8.10%

Sulfur: 6.525 mg / 30.199 mg = 21.60 %

Oxygen: 100% - (48.58% + 8.10% +21.60%) = 21.72%

Number of moles of each element is then determined:

Number of moles = percentage mass/molar mass

Carbon: 48.58/12 = 4.07

Hydrogen: 8.10/1 = 8.10

Sulfur: 21.60/32 = 0.68

Oxygen: 21.72/16 = 1.36

Dividing with the smallest amount to obtain a whole number mole ratio

Carbon: 4.07 ÷ 0.68 = 6

Hydrogen: 8.10 ÷ 0.68 = 12

Sulfur: 0.68 ÷ 0.68 = 1

Oxygen: 1.36 ÷ 0.68 = 2

Therefore, the empirical formula of the chemical compound is C₆H₁₂SO₂

Answer:

1. Empirical formula => C₂H₃O

2. Molecular formula => C₆H₉O₃

Explanation:

From the question given above, the following data were obtained:

Mass of compound = 50 g

Mass of Carbon = 24.66 g

Mass of Hydrogen = 3.43 g

Molecular weight of compound = 146.0 amu

Empirical formula =?

Molecular formula =?

Next, we shall determine the mass of oxygen in the compound. This can be obtained as follow:

Mass of compound = 50 g

Mass of C = 24.66 g

Mass of H = 3.43 g

Mass of O =?

Mass of O = mass of compound – ( mass of C + mass of H)

= 50 – (24.66 + 3.43)

= 50 – 28.09

= 21.91 g

1. Determination of the empirical formula.

Mass of C = 24.66 g

Mass of H = 3.43 g

Mass of O = 21.91 g

Divide by their molar mass

C = 24.66 / 12 = 2.055

H = 3.43 / 1 = 3.43

O = 21.91 / 16 = 1.369

Divide by the smallest

C = 2.055 / 1.369 = 2

H = 3.43 / 1.369 = 3

O = 1.369 / 1.369 = 1

Therefore, the empirical formula of the compound is C₂H₃O

2. Determination of the molecular formula.

Molecular weight of compound = 146.0 amu

Empirical formula => C₂H₃O

Molecular formula =?

Molecular formula = [C₂H₃O]ₙ = molecular weight

Thus,

[C₂H₃O]ₙ = 146

[(12×2) + (3×1) + 16]n = 146

[24 + 3 + 16]n = 146

43n = 146

Divide both side by 43

n = 146 / 43

n = 3

Molecular formula = [C₂H₃O]ₙ

Molecular formula = [C₂H₃O]₃

Molecular formula = C₆H₉O₃

Answer:

4.42x10⁻⁶ m³

Explanation:

Primero convertimos 100 gramos a kilogramos:

Ahora se puede calcular el volumen que ocuparán 0.100 kg de osmio, usando la densidad dada por el problema:

La respuesta es 4.42x10⁻⁶ m³.

Answer:

Option D. 230 J

Explanation:

We'll begin by calculating the temperature change of the iron. This can be obtained as follow:

Initial temperature (T₁) = 50 °C

Final temperature (T₂) = 75 °C

Change in temperature (ΔT) =?

ΔT = T₂ – T₁

ΔT = 75 – 50

ΔT = 25 °C

Thus, the temperature change of the iron is 25 °C.

Finally, we shall determine the amount of heat energy used. This can be obtained as follow:

Mass (M) = 20 g

Change in temperature (ΔT) = 25 °C

Specific heat capacity (C) = 0.46 J/gºC

Heat (Q) =?

Q = MCΔT

Q = 20 × 0.46 × 25

Q = 230 J

Thus, the amount of heat used was 230 J

Answer:

1.054 x 10²⁴ molecules

Explanation:

In order to convert moles of any given substance into a number of molecules, we need to use Avogadro's number, which states the number of molecules -or atoms, in the case of elements- present in one mol:

We now convert 1.75 moles into molecules:

Answer:

Bacteria

Explanation:

Answer:

False

Explanation:

There is a water cycle wherever there is water. If it is cold, the water cycle will just be very slow.

Answer:

it isnt possible to answer this without you providing the "organelle illustrated above".

Explanation:

please provide the "organelle illustrated above".

Answer: The concentration of solution made by the student is 1 M.

Explanation:

Molarity is defined as the amount of solute expressed in the number of moles present per liter of solution. The units of molarity are mol/L.

The formula used to calculate molarity:

[tex]\text{Molarity of solution}=\frac{\text{Number of moles of solute}\times 1000}{\text{Volume of solution (mL)}}[/tex]       .....(1)

Given values:

Moles of solute = 0.5 moles

Volume of solution = 500 mL

Plugging values in equation 1:

[tex]\text{Molarity of solution}=\frac{0.5\times 1000}{500}\\\\\text{Molarity of solution}=1M[/tex]

Hence, the concentration of solution made by the student is 1 M.

Answer:

2 moles!

Explanation:

Hi i hope this helped! I researched it and 2 moles was what came up first.

The balanced reaction is

(Na3PO4)12H2O + 9(BaCl2)2H2O → 6Ba3(PO4)2 + 36NaCl + 10H2O

molar mass of (Na3PO4)12H2O = 380 g/mol

given mass of (Na3PO4)12H2O = 0.990 g

moles of (Na3PO4)12H2O = given mass/molar mass

moles of (Na3PO4)12H2O = 0.990/380= 0.0026 mole

one mole of (Na3PO4)12H2O forms 6 mole of Ba3(PO4)2

0.0026 mole of (Na3PO4)12H2O forms 0.0026×6 =

0.0156 mole of Ba3(PO4)2

mass of 0.0156 moles of Ba3(PO4)2 is = 0.0156 × 601.9 g = 9.40 gram

Answer:

Mole = number of molecules divided by the avogadro's constant.

Molar mass of NaCI =23 + 35.5 =58.5g/mol

Mass= moles multipled by molar mass of NaCI

M

Answer:

Therefore, it can be said that sugar molecules whether in crystal or cube form do not dissolve in ice tea.

Explanation:

Sugar molecules easily dissolve in warm or hot tea. However, in iced tea sugar does not dissolve it does not matter whether you use sugar cubes or sugar crystals.

This happens because of the entropy. The entropy of warm water is high as it has fast-moving molecules, whereas the entropy of ice water is negligible. hence, sugar molecules do not dissolve in ice tea.

Therefore, it can be said that sugar molecules whether in crystal or cube form do not dissolve in ice tea.

Answer:

A glacier is a large mass of snow and ice that has accumulated over many years and is present year-round. In the United States, glaciers can be found in the Rocky Mountains, the Sierra Nevada, the Cascades, and throughout Alaska. A glacier flows naturally like a river, only much more slowly. At higher elevations, glaciers accumulate snow, which eventually becomes compressed into ice. At lower elevations, the “river” of ice naturally loses mass because of melting and ice breaking off and floating away (iceberg calving) if the glacier ends in a lake or the ocean. When melting and calving are exactly balanced by new snow accumulation, a glacier is in equilibrium and its mass will neither increase nor decrease.

In many areas, glaciers provide communities and ecosystems with a reliable source of streamflow and drinking water, particularly in times of extended drought and late in the summer, when seasonal snowpack has melted away. Freshwater runoff from glaciers also influences ocean ecosystems. Glaciers are important as an indicator of climate change because physical changes in glaciers whether they are growing or shrinking, advancing or receding provide visible evidence of changes in temperature and precipitation. If glaciers lose more ice than they can accumulate through new snowfall, they ultimately add more water to the oceans, leading to a rise in sea level (see the Sea Level indicator). The same kinds of changes occur on a much larger scale within the giant ice sheets that cover Greenland and Antarctica, potentially leading to even bigger implications for sea level. Small glaciers tend to respond more quickly to climate change than the giant ice sheets. Altogether, the world’s small glaciers are adding roughly the same amount of water to the oceans per year as the ice sheets of Greenland and Antarctica combined. During the last two decades, they added more water overall to the oceans than the ice sheets did.

Explanation:

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Because they offer a variety of essential functions, including as controlling river flows and water supply, safeguarding coastal areas from floods, and preserving biodiversity, glaciers are a crucial component of human survival.

First, many people throughout the world rely heavily on glaciers as a supply of freshwater. When glaciers melt, they release water that has been stored and is subsequently utilised for agriculture, drinking water, and other things.

In dry areas with limited access to other freshwater sources, this water is very crucial. As a natural reservoir, glaciers may also hold a lot of water during the winter and release it gradually throughout the summer. This helps to control river flows and avoid flooding.

Second, glaciers contribute significantly to the global climate.system of climate. Large volumes of carbon dioxide and other greenhouse gases are released as glaciers melt, which can contribute to global warming. Glaciers may also reflect sunlight, which aids in cooling the surroundings around them.

High-altitude places, where glaciers can help regulate temperatures and avert catastrophic weather occurrences, are particularly crucial for this cooling impact. Last but not least, glaciers are crucial for the preservation of biodiversity. Numerous types of plants, animals, and microorganisms find a special niche in glaciers. These species may be disrupted by glacier melting, which might result in the extinction of entire ecosystems. The environment and the communities who rely on it may be significantly impacted by this.

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Answer: The Answer would be C

Explanation: A spectrum is a Range of Wavelengths and Frequencies of Electromagnetic Radition.

The statement that describe spectrum is a range of wavelengths or frequencies of electromagnetic radiation.

Spectrum arrangement or electromagnetic radiations base on their wavelength and frequency which can be visible light, ultraviolet, and infrared light. An instrument that is use for visual observation of spectra is called a spectroscope.

Therefore, The statement that describe spectrum is a range of wavelengths or frequencies of electromagnetic

radiation.

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Answer: The pressure in the tires at that point is 528.52 kPa.

Explanation:

Given: [tex]T_{1}[/tex] = 500 K,          [tex]P_{1}[/tex] = 500 kPa

[tex]T_{2}[/tex] = 315 K,              [tex]P_{2}[/tex] = ?

According to Gay-Lussac's law, at constant volume the pressure of a gas is directly proportional to temperature.

Formula used to calculate the pressure is as follows.

[tex]\frac{P_{1}}{T_{1}} = \frac{P_{2}}{T_{2}}[/tex]

Substitute the values into above formula as follows.

[tex]\frac{P_{1}}{T_{1}} = \frac{P_{2}}{T_{2}}\\\frac{500 kPa}{298 K} = \frac{P_{2}}{315 K}\\P_{2} = 528.52 kPa[/tex]

Thus, we can conclude that the pressure in the tires at that point is 528.52 kPa.

b

b357

Answer:

2Fe +3 H2SO4  Fe2(SO4)3 + 3H2

2*56g. 3*98g➔400g. +6g

we have

2*56 g of Fe gives 400g of iron (III ) sulfate

now

100g of Fe gives=400/112*100=357g of iron (III ) sulfate

[tex]\:[/tex]

B is your answer.!

Answer:

sodium fluoride

Explanation:

When we add sodium fluoride to a solution of a given mixture, we get barium fluoride from Ba, which would be an insoluble salt, and silver fluoride from Ag, which would be a soluble salt. 

The solubility rule will be used to determine the barium salt that forms as a precipitate and leaves Ag+ salt in the solution.

From the following equations, we will see that the precipitate is formed in Ba but Ag remains dissolved in the solution.

[tex]Ba(NO_3)_2{(aq)} + 2NaF_{(aq)} \to BaF_{2(s)} +2NaNo_{3(aq)}[/tex]

[tex]AgNo_{3(aq)} +NaF_{(aq)} \to AgF_{(aq)} + NaNO_{(aq)}[/tex]