a sample of iodine-131 has an activity of 200 mci. if the half-life of iodine-131 is 8.0 days, what activity is observed after 16 days?

The partial pressure of hydrogen is 473.25 mm of Hg.

What is Dalton s law?

Dalton’s Law, also known as Dalton’s Law of Partial Pressures, states that the total pressure exerted by a mixture of gases is equal to the sum of the partial pressures of the individual gases. This law was proposed by English chemist John Dalton in 1801. In a mixture of gases, each gas has an individual pressure, and the total pressure is the sum of the pressures of each of the gases. This law is based on the fact that each gas in a mixture behaves independently of the other gases, and that the total pressure of the mixture is equal to the sum of the partial pressures of each gas. The partial pressure of a gas is determined by the concentration of the gas in the mixture and the total pressure of the mixture.

Pi = Xi Pt
partial pressure of gas = mole fraction of that gas × total pressure
2NH3 ⇒N2+ 3H2
mole fraction of hydrogen =3/4 = 0.75
partial pressure of H2 = 0.75×631 mm of Hg = 473.25 mm of Hg.
(1 mm of Hg = 1 torr)

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The four types of chemical exposure is inhalation, ingestion , injection and skin or eye contact.

There are four routes of  chemical exposure are given as :

in inhalation chemicals that take form in gas vapor or particulates are be easily inhaled. ingestion as like inhalation can cause the toxic chemicals that travels to the organ. skin or eye contact is when the chemicals comes in contact with eye and skin and gives rashes. injection is when you have the cut or other tear in the skin the chemicals will absorbed.

Thus, inhalation, ingestion , injection and skin or eye contact are the main routes of the chemical exposure.

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The rank of the compounds in order of increasing reactivity in electrophillic aromatic substition is C, A and B.

OCH3 is electron releasing group . whenever electron releasing group present on benzene ring that molecule is highly reactive .

-Cl is withdrawing group . whenever the molecule is contain withdrawing group it is least reactiveReactivity is a somewhat ambiguous term in chemistry. It seems to embody both thermodynamic and kinetic factors.

That is, whether a substance reacts and how quickly it reacts. Both factors are actually different and generally temperature dependent. For example, it is commonly claimed that the reactivity of Group I metals (Na, K, etc.) increases towards the bottom of the periodic table groups, or that the reactivity of hydrogen is evidenced by its reaction with oxygen.

In fact, the reaction rate of alkali metals (as evidenced by their reaction with water, for example) is not only a function of position within the group, but also of particle size. Hydrogen does not react with oxygen, although it has a very large equilibrium constant, except when the flame initiates a radical reaction and causes an explosion.

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The best reagent in the bin for each of these reactions involving cyclohexylmethanol to cyclohexyl methyl bromide is NaBr.

The reagent used in the reaction of the cyclohexylmethanol to cyclohexyl methyl bromide is NaBr. the reaction is given as follows :

cyclohexylmethanol +   NaBr    ------>   cyclohexyl methyl bromide

The reagent is used in the chemical reaction in order to find out the the another substances if it is present. A reagent is a substance is used to perform the laboratory test.  the reagent is used to perform the above reaction is NaBr.

Therefore, NaBr is the reagent used in cyclohexylmethanol to cyclohexyl methyl bromide.

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The final temperature if the gas is compressed to 0.800 m3 and the pressure rises to 0.820 × 10^5 pa is 357.8 K

P1V1/T1=P2V2/T2

T2=P2V2T1/P1V1

T2= 0.820 × 10^5×0.800×300÷0.500 × 10^5×1.1 m^3

T2=357.8 K

The characteristic of matter that represents the amount of energy used in the motion of its constituent particles is its temperature. It provides a comparison of a material's heat or cold content. Absolute zero is the designation for the coldest possible temperature. It is the temperature where there is the least amount of thermal mobility in the particles (not the same as motionless). The Kelvin scale reads 0 K, the Celsius scale reads 273.15 C, and the Fahrenheit scale reads 459.67 F. A thermometer is the device used to measure temperature. The Kelvin (K) is the SI unit of temperature, while other temperature scales are more frequently employed in day-to-day settings. In order to describe temperature, one can use the Zeroth Law of Thermodynamics.

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Nutritionists express energy in calories, which are 1000 real calories. One real calorie is equivalent to 4.18 joules, the universal energy unit and hence, one nutrition calorie is equivalent to: 4.18 kilojoules.

In the nutrition world, calorie indicate amount of energy in foods. As a food calorie is equal to 1,000 small calories, it is also called a large calorie or a kilocalorie (kcal). Food calories come from these four sources: carbohydrates, proteins, fats, and alcohol.

The calorie and nutrient content of single ingredients and individual foods  is found in the USDA's National Nutrient Database. Most of the packaged foods list information in the Nutrition Facts panel.

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At 50 degrees Celsius, potassium chloride is soluble in 43.0 grams per 100 grams of water.

The metal halide salt potassium chloride, also known as potassium salt or KCl, is made of these two elements. It has an appearance of a vitreous crystal and is odourless. The substance easily dissolves in water and has a salty flavour to its solutions. Dried lake sediments from long ago can be used to make potassium chloride. In addition to being used as a fertilizer, KCl is also utilized as an E number additive (E508) in food processing, as well as in science, medicine, and home water softeners (in place of sodium chloride salt).

When combined with sodium chloride, it forms the compound sylvinite, which is found naturally as the mineral sylvite.

Due to the fact that the availability of potassium restricts the growth of many plants, the bulk of the potassium chloride generated is used to create fertilizer, known as potash.

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The organic compound that do not contain the carbonyl group is alcohol, which means option D is the correct choice.

The carbonyl group refers to C=O. It is contained in aldehyde, Ketones, carboxylic acids , esters, amides and acyl chlorides. They are not found in alcohols. The alcohols are generally ROH. They do not contain any carbon-oxygen unsaturated bond in their structure hence the answer. Alcohol is a useful group which you are likely acquainted with. In natural chemistry, the time period alcohol refers to a compound containing the OH (hydroxy) group.

Hence, the correct choice is D.

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Complete question:

Which one of the following classes of organic compound does not contain the carbonyl (C=O) group?A) aldehydesB) carboxylic acidsC) ketonesD) alcoholsE) esters

Answer:

An entirely new substance with new properties forms as a result of the change.

Since Julie is trying to determine what organelle is damaged, and preventing homeostasis, the organelle  is contractile vacuole.

A specific sort of vacuole that controls the amount of water in a cell is called a contractile vacuole. Freshwater environments have hypotonic solute concentrations, meaning that they are higher inside the cell than outside. Osmosis causes water from the outside environment to build up in the cell under these circumstances.

Therefore, through osmoregulation, the contractile vacuoles of amoebas assist them in maintaining homeostasis. The ongoing process of keeping solvent and solute levels in the cell in a healthy range is known as osmoregulation. Water serves as both the solute and the solvent in a reaction.

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Answer:

G

Explanation:

The atmosphere is divided into five different layers, based on temperature. The layer closest to Earth's surface is the troposphere, reaching from about seven and 15 kilometers (five to 10 miles) from the surface. The troposphere is thickest at the equator, and much thinner at the North and South Poles.

answer is G Atmosphere

The Conclusion, methanol poisoning can purpose histological adjustments in liver tissues.

Most importantly in instances with imply blood and vitreous humor methanol stages extra than 127 ± 38.nine mg/dL a couple of pathologic capabilities have been detected. Methanol is transformed to formaldehyde thru alcohol dehydrogenase and formaldehyde is transformed to formic acid (formate) thru aldehyde dehydrogenase.

The methanol is transformed through the liver to arsenic and may wreck the frame over time. This is real because it become discovered withinside the liver of the hen. Methanol is transformed through the liver to arsenic and may wreck the frame over time.

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The half-life of strontium-90 is 28 years. how long will it take a 50-mg sample to decay to a mass of 22 mg it took 13 years.

What is half-life?

The period of time it takes for one-half of a radioactive isotope to decay is known as the half-life. An individual radioactive isotope's half-life is unaffected by environmental factors and is independent of the isotope's starting concentration.

What is decay ?

Reduction in amount, activity, or force, for instance. Chemistry: Radioactive material's radioactive atom content spontaneously decreases. Spontaneous disintegration in physics (as of an atom or a particle)

Using the half life formula

A=A₀ 2(-t/h)

Where,

A = restultant amount

A₀= initial amount

t= decay time

h= half life of substance

=36=50(2)^(-t/28)

2^(-t/28)= 36/50

2^(-t/28= 0.72

taking log both sides

we have t=-28 ln(0.72)/ln2

t=13.27

t= 13 years.

Therefore, the half-life of strontium-90 is 28 years. how long will it take a 50-mg sample to decay to a mass of 22 mg it took 13 years.

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35.53 grams of cl2 are generated by a current of 5.55 amperes flowing for 290 minutes in the electrolysis of aqueous NaCl.

What is electrolysis?

The process of electrolysis involves passing an electric current through a substance in order to modify its chemical composition.

[tex]NaCl[/tex]  → [tex]Na^{+} +Cl^{-}[/tex]

[tex]2Cl^{-}[/tex]  →   [tex]Cl^{2} +2e^{-} , n=2[/tex]

Equivalent mass (E) is calculated as,

[tex]E=\frac{71 g}{2} \\=35.5 grams[/tex]

Time (t)= 290 minutes

=290 x 60 sec

=17400 sec

I= 5.55 Amp

The formula is given as,

m=ZIt

where Z= equivalent weight/96500

= 35.5 g/96500

Substituting the values in the above formula, we get

[tex]m=\frac{35.5}{96500} .5.55.17400\\=35.53 grams[/tex]

Therefore, 35.53 grams of cl2 are generated by a current of 5.55 amperes flowing for 290 minutes in the electrolysis of aqueous nacl.

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There are four types of chemical bonds essential for life to exist: Ionic Bonds, Covalent Bonds, Hydrogen Bonds, and van der Waals interactions. We need all of these different kinds of bonds to play various roles in biochemical interactions. These bonds vary in their strengths.

To play a variety of roles in biochemical interactions, we require all of these diverse sorts of linkages. The tensile strength of these linkages varies. In chemistry, we consider the range of strengths between ionic and covalent bonds to be overlapping. This indicates that in water, ionic bonds usually dissociate. As a result, we shall consider these bonds from strongest to weakest in the following order:

Covalent is followed by ionic, hydrogen, and van der Waals.

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According to the following reaction, the volume of KCl solution required to react with 50ml of 0.21M Pb(NO3)2 solution is 86mL (based on chemical equation).

It is an equation that make use of chemical formulae and symbols to represent chemical reactions. The left-hand side of a chemical equation represents the reactants and the right-hand side represents the products.

How to calculate the volume of KCl solution using chemical equation?

First, let's write the chemical equation
2KCl + Pb(NO₃)₂ -> PbCl₂ + 2KNO₃

Given from the question

Molarity of Pb(NO₃)₂ = 0.210M

Volume of Pb(NO₃)₂ solution = 50mL = 50 / 1000 = 0.05L

Molarity of Pb(NO₃)₂ solution = Number of moles of Pb(NO₃)₂ / volume of solution in L

0.210M = Number of moles of Pb(NO₃)₂ / 0.05L

Number of moles of Pb(NO₃)₂ = 0.0105 mol

Using stoichiometric coefficients from the chemical equation above

1 mol Pb(NO₃)₂ requires 2 moles of KCl

so, 0.0105 mol Pb(NO₃)₂ requires (2 * 0.0105) moles KCl = 0.021mol KCl

Number of moles of KCl = 0.021 mol

Molarity of KCl solution = 0.244M

Molarity of KCl solution = Number of moles of KCl / Volume of KCl solution in L

0.244 = 0.021 / volume of solution in L

Volume of KCl solution = 0.021 / 0.244

= 0.0861 (rounded) L * 1000 mL

= 86mL

Therefore, the volume of KCl solution required is 86mL.

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Because there is only one unpaired electron in the valence shell of each Cl atom, or because only one electron is needed to complete the octet of the valence shell of Cl, two Cl atoms are connected by a single bond.

They thereby contribute to each other's stabilization by the unpaired electron.

A chemical link is formed when two atoms in a molecule share one pair of electrons, particularly when the atoms can share many pairs of electrons (see the double bond, triple bond). A single bond is a two-valence electron chemical link formed between two atoms. In other words, where the link is formed, the atoms share a pair of electrons. Thus, a single bond is a particular kind of covalent link.

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The solubility of organic compounds in water can vary widely. Here is the order of solubility of the compounds you listed, from most to least soluble:

The solubility of a compound in water can depend on a variety of factors, such as the chemical structure of the compound, temperature, and the presence of other substances. Solubility is the ability of a substance, known as the solute, to dissolve in a solvent to form a homogeneous solution. The solubility of a compound is usually expressed in terms of the maximum amount of the compound that can dissolve in a given amount of solvent at a particular temperature.

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The piece of glassware calibrated "TD" will contain and transfer the stated volume the stated volume slightly more than

Volumetric flasks, burets and pipets are the maximum correct with tolerances of much less than 0.2%. To obtain those accuracies the character the use of the tool desires to apply the right approach and the measurements want to made on the temperature for which the glassware changed into calibrated (commonly 20 stages C).To suggest this difference, volumetric glassware is commonly marked TD which means to supply or TC which means to comprise.

Certain styles of pipets, in particular micropipets, are designed to comprise a positive extent of liquid and those are marked piece of glassware calibrated "TD" will comprise and switch the said extent the said extent said precisely; precisely barely greater than; precisely barely much less than; precisely precisely: barely much less than barely much less than; barely greater than.

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Clouds are formed when water evaporates

When billions of tiny dust particles carrying water droplets come together they form a cloud

Clouds can be formed on both warm and cold fronts.

A cloud is a mass of water drops or ice crystals suspended in the atmosphere. Clouds form when water condenses in the sky. The condensation lets us see the water vapor. There are many different types of clouds. Clouds are an important part of Earth's weather and climate.

When warm air rises, it expands and cools. Cool air can't hold as much water vapor as warm air, so some of the vapor condenses into tiny pieces of dust that are floating in the air and forms a tiny droplet around each dust particle. When billions of these droplets come together they become a visible cloud.

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Fundamentally, atoms are attempting to achieve the most stable (lowest-energy) state possible. When an atom's valence shell is fully populated with electrons or when they comply with the octet rule, a large number of them become stable (by having eight valence electrons).

What are electrons?

It is possible for an electron to be free or linked to an atom. An electron is a negatively charged subatomic particle (not bound). One of the three main types of particles inside an atom, along with protons and neutrons, is an electron that is linked to the atom. The nucleus of an atom is composed of protons, neutrons, and electrons.

Just one electron and one proton are present in the hydrogen atom, for instance. On the other hand, the uranium atom possesses 92 protons, which means 92 electrons.

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The  potential of this cell is +0.0385.

Zn | Zn2+(0.050 M) || Zn2+(1.00 M) | Zn

Zn(s) ==> Zn2+(0.050 M)       (oxidation on the left side)

Zn2+(1.00M) + 2e- ==> Zn(s)  (reduction on the right side)

Zn2+(1.00M) ==> Zn2+(0.050M)

Ecell = Eºcell - RT ln Q and assuming this situation is at 25ºC (298K), we have...

Ecell = Eºcell - 0.0592 / 2 log Q  

Q = 0.050 / 1.00 = 0.05

Ecell = 0 - 0.0296 * log 0.05

Ecell = -0.0296 * -1.301

Ecell = +0.0385  (note the potential is positive, meaning the reaction is spontaneous)

Also note that this is the INSTANTANEOUS cell potential. As time goes on, the cell potential will become ZERO.

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Yes, all the liquid will evaporates,

given that :

vapor pressure of liquid carbon disulfide = 100mmHg = 0.1315 kpa

temperature = 268 K

volume of the container = 370 mL = 0.370 L

using ideal gas equation we get :

PV = n R T

n = P V / R T

n = ( 0.315 × 0.370 ) / ( 0.0823 × 278)

n = 0.0050 mol = 5.0 × 10⁻³ mol

number of moles of CS₂ = mass / molar mass

                                        = 0.0979 / 76.139

                                        = 0.00128 mol

                                        = 1.2 × 10⁻³ mol

it is clear that , the vapor pressure of liquid carbon disulfide, , is 100. mm hg at 268 k. a 0.0979 g sample of liquid is placed in a closed, evacuated 370. ml container at a temperature of 268 k. yes the temperature remains constant, all of the liquid evaporate.

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The 3 mandatory statements that must be seen on label are the product identity , the weight and best before or use by date.

The label should contains the product identity that is the name of the food and the ingredients used. the whole description of the nutrition values of the product. The product identity also includes the company name, trade makers. the net weight of the product should be labeled. the net contents should be listed according to the consistency of the product.

The label should also includes the best before use or use by the date is the expiry date of the product.

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In this question, we are asked to determine the number of neutrons of an arsenic atom.

When we are given with the atomic number of Arsenic atom, i.e. 27 and mass number 60

We know that Atom is made up of three major sub atomic particles, i.e. electron, proton, and neutron.

Out of these three, electron is negatively charged sub atomic particle tat revolves around the nucleus.

Proton is positively charged sub atomic particles that resides inside the nucleus along with neutral neutrons.

As the majority of mass of atom is collected inside the nucleus, the mass number refers to the sum of the number of protons and number of neutrons.

and Atomic number is equal to the number of Protons.

So,

Number of neutron = Mass number - Atomic number

Number of neutron = 60 - 27

Number of neutron = 33

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The correct option is a). The product has a lower Rf value on a silica gel TLC plate because it is more polar than the starting methyl benzoate.

Describe a TLC plate.

A glass, metal, or plastic sheet that has been thinly covered with a solid adsorbent (usually silica or alumina)is known as a TLC plate. Near the bottom of this plate, there is a tiny bit of the mixture to be tested.

Silica gel has lots pores with contains water, and we know that water is polar. So we can say that our stationary phase here silica gel is polar. In chemistry we say 'like dissolves like' therefore polar substance interacts with polar substances. If interaction is more than Rf value will be less. Rf value is nothing but the distance travelled by molecule on TLC plate. Here methyl m nitrobenzoate has nitro group which is polar in nature therefore it will interact with water in silica gel and she this it will travel less distance therefore Rf value is lower than methyl benzoate which does not interact with water in silica gel as it has no polar groups therefore runs faster and travels more distance hence the high Rf.

Therefore, the correct option is a). The product has a lower Rf value on a silica gel TLC plate because it is more polar than the starting methyl benzoate.

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Start with the ideal gas law in its standard form:

PV=nRT

Dividing both sides by RT, we get

n=PV/RT

causes this to cancel from the right side, solving the equation for n.

In thermodynamics, Ideal gas law is a well-defined approximation of the behavior of many gases under diverse conditions.

Ideal Gas Equation is the combination of empirical laws like Charle’s law, Boyle’s law, Gay-Lussac’s law, and Avogadro’s law.

Ideal Gas Equation is the equation defining the states of the hypothetical gases expressed mathematically by the combinations of empirical and physical constants. It is also called the general gas equation.

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Water vapor (H2O) is an important greenhouse gas. The correct option is C

Atmospheric Gases are gases located in the earth atmosphere. These gases are include oxygen and nitrogen making up 99% of the air. The remaining 1% mostly contains argon, carbon dioxide and several other gases.

The atmosphere supports life and is also needed for the water cycle and weather while gases in the air allow us to hear most of the sounds in our world.

Therefore water vapor (H2O) is an important greenhouse gas. The correct option is C

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The number of molecules in 12.5 moles of CaCO₃ is 7.525×10²⁴ molecules

From Avogadro's hypothesis, we understood that

1 mole of CaCO₃ = 6.02×10²³ molecules

Using the above information, we can obtain the number of molecules in 12.5 moles of CaCO₃ as illustrated below:

From Avogadro's hypothesis,

1 mole of CaCO₃ = 6.02×10²³ molecules

Therefore,

12.5 moles of CaCO₃ = (12.5 moles × 6.02×10²³ molecules) / 1 mole

12.5 moles of CaCO₃ = 7.525×10²⁴ molecules

Thus, we can conclude from the calculation made above that the number of molecules is 7.525×10²⁴ molecules

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