One of the radioactive isotopes used in chemical and medical research is iodine-125, which has a half-life of 61 days. how long would it take for 0.25 g to remain of a 1.00 g sample of iodine-125?

According to the bohr model, the energy change in joules that occurs E=−1.36×10∧−19J, when an electron falls from the n = 4 to the n = 2 energy level in a hydrogen atom.

The Bohr model, also known as the Rutherford-Bohr model, was first proposed by Niels Bohr and Ernest Rutherford in 1913 and describes an atomic system with an orbiting system of electrons and a small, dense nucleus that is similar to the Solar System in structure but is attracted by electrostatic forces rather than gravity.

1) The orbits of the electrons surrounding the nucleus are circular and have a constant energy.

2) The electron only rotates in orbits with angular momentum greater than or equal to nhi/2π³.

Only when an electron transitions from one orbit to another can energy become realised or absorbed in the form of a photon.

To learn more about bohr model go to -

https://brainly.com/question/4138548

#SPJ4

In a first-order reaction, it takes 23.02 days for 68 percent of the chemical to be destroyed.

Given,

fee constant for the destruction of pollutant = 0.1/day

We ought to discover the number of days it'll take for sixty eight percent of the chemical to be destroyed.

[A] = [A]₀e^⁻kt

in which [A] is the present awareness, and

[A]₀ is the initial awareness

k is the price of decrement

[A]₀ = 1

[A] = 0.1

Or, t =㏑(10)/k

Or, t = 2.302/zero.1

Or, t = 23.02 days.

for this reason the wide variety of days required for the destruction of sixty eight percent of chemicals is 23 days.

To learn more about the first-order reaction, visit: https://brainly.com/question/10898529

#SPJ4

It is impossible for an element to have an atomic number of 110.5 because atoms of an element all have the same whole number of protons. Thus, option C is correct.

The atomic number is the number of protons in the nucleus of an atom. The number of protons defines the identity of an element. The atomic number of an atom is equal to the number of protons in the nucleus of an atom or the number of electrons in an electrically neutral atom.

For example, in a sodium atom, there are 11 electrons and 11 protons.

Thus, the atomic number of Na atom = number of electrons = number of protons is equal to 11.

The atomic number is based only on the number of protons in the nucleus of an atom. Since this is a count of whole numbers, it cannot be a decimal. It's either element 110 or 111, not 110.5.

There is no half proton in the atom, hence we can not have an atomic number of 110.5.

To learn more about atomic number of elements, refer to below link:

https://brainly.com/question/14190064

#SPJ2

Ionization energy : the minimum amount of energy demands to detach an electron from an isolated atom.

Ionization energy also known as potential energy.

The charge of the nucleus increases from side to side in a row and so there is an increase in the attraction in the middle of the nucleus and the surrounding electrons.  As we move from side to side in a periodic table from left to right, the nuclear charge increases. This is because of increasing nuclear charge, which concludes in the topmost electron being more strongly leap to the nucleus.

To know more about Ionization energy here :

https://brainly.com/question/16243729?referrer=searchResults

#SPJ4

Hydrofluoric acid, HF in an aqueous form having molecular weight of 20.01 have concentration of 48-50% w/w in aqueous solution/water with a pH of 5.89.

HF in an aqueous solution ionizes like the other acids. It is extremely corrosive. It dissociates in water as -

                                        HF + H₂O ⇆ H₃O⁺ + F⁻  

Hydrofluoric acid is much stronger when concentrated. If concentration increases and approach to 100%, the acidity of acid increases and the base forms a bond.

                                        3HF ⇆ H₂F⁺ + HF₂⁻

The presence of hydrogen ion in an aqueous solution makes the HF acidic. HF is soluble with boiling point 19.5°C and melting point 0f -83.6°C

To learn more about HF,

brainly.com/question/3102869

#SPJ4

One-half cup of black-eyed peas contains at least 100 mcg of folate per serving.

In infants and the women with poor folic acid intakes, the neural tube defects (NTDs), or failures in the closure of the neural tube are more common. For the normal formation of the spinal cord, proper closure of the neural tube is required.

Within the first month of gestation, the neural tube begins to close, often before a person realizes that she is pregnant.

Therefore, 0.4 mg of folic acid should be taken every day, while consuming dietary sources of folate, i.e. intake of folate rich diet/meal by all people who are capable of becoming pregnant.

One-half cup of black-eyed peas contains at least 100 mcg of folate. Ready-to-eat breakfast cereal contains 200 mcg of folate and a slice of bread contains 20 mcg, and not 100 mcg of folate. One-half cup of broccoli and a cup of pasta contain 50 mcg, not 100 mcg of folate.

Complete question is-

Which food contains at least 100 mcg of folate per serving? one, some, or all responses may be correct.

1. Bread

2. Broccoli

3. Cooked pasta

4. Black-eyed pasta

5. Ready-to-eat breakfast cereal

To learn more about folate,

brainly.com/question/10228312

#SPJ4

A tetrahedral carbon is sp3 hybridized while a linear carbon is sp hybridized.

Carbon is a chemical element with the symbol C and atomic number 6. It is a non-metal and is tetravalent. That atom donates four electrons to form a covalent chemical bond. It belongs to group 14 of the periodic table. Carbon makes up only about 0.025% of the Earth's crust.

Carbon is an essential element for all life forms on earth. Carbon uptake and release are part of all plant and animal life, whether these life forms take up carbon to help make food or release carbon as part of respiration. Carbon is constantly moving from place to place. Carbon is also found in fossil fuels such as petroleum (crude oil), coal, and natural gas. Carbon is also found in dead, decaying animals and animal waste soils. Carbon is stored in the biosphere of plants and trees.

Learn more about carbon  here

https://brainly.com/question/141693

#SPJ4

A central theme in chemistry is that we study Observable changes in matter to understand their Unobservable causes.

Matter is a substance made up of a variety of sorts of particles that occupies physical house and has inertia. According to the standards of current physics, the a variety of sorts of particles every have a particular mass and size. The most acquainted examples of fabric particles are the electron, the proton and the neutron.

Learn more about Matter here:

https://brainly.com/question/4513444

#SPJ4

Answer:

a solution which resists changes in pH when acid or alkali is added to it is known as Buffer solution

An atom of zirconium which has a mass number of 96 has 37 electrons in it.

Atomic number 40 and the letter Zr are used to identify the chemical element zirconium. Zircon is the name of the mineral from which zirconium gets its name. The name has a connection to the most significant source of zirconium, the Persian word zargun (zircon; zar-gun, "gold-like" or "like gold").

This transition metal closely resembles titanium and, to a lesser extent, hafnium. It is glossy, grey-white, and strong. Although it is used sparingly as an alloying agent due to its high corrosion resistance, zirconium is mostly utilised as a refractory and an opacifier.

Inorganic and organometallic compounds like zirconium dioxide and zirconocene dichloride are both formed by zirconium. There are five stable isotopes that are found in nature. The biological function of zirconium compounds is unknown.

Learn more about zirconium

https://brainly.com/question/1347130

#SPJ4

The molar mass of vitamin if it contains 4.34% of cobalt is 1358 g/mole.

Molar mass is the mass of 1 mole of the compound.One mole of compound contains Avogadro's number of molecules.So,molar mass is mass of Avogadro's number of molecules.

Molar mass is also defined as mass of the sample divided by the amount of substance, measured in moles .It is a bulk quantity not a molecular property of substance. The SI unit of molar mass is kilogram per mole.

In this problem,vitamin has 1 cobalt atom .The atomic mass of cobalt is 58.93 g/mole.So according to the definition,mass of 1 mole of cobalt is 58.93 g =4.34% mass of 1 mole of vitamin.

To find 100% mass of 1 mole of vitamin

58.93/4.43×100=1358 g

Hence,the molar mass of vitamin is 1358 g.

To learn more about  molar mass click here:

https://brainly.com/question/13152455

#SPJ1

The protons neutrons and electrons are there in a neutral atom

In a neutral atom of ⁶⁰Co (cobalt-60), there are 27 protons, 27 electrons, and 33 neutrons.

We have to find the number of protons, neutrons, and electrons in a neutral atom of ⁶⁰Co (cobalt-60).

The number of protons = The atomic number.

The atomic number of cobalt is = 27

Therefore, the protons are 27

As protons and electrons are equal. Then, the number of electrons is 27.

The number of Neutrons = Atomic number - Number of protons.

Neutrons = 60 - 27

Or, neutrons = 33

Hence, the number of neutrons is 33, electrons are 27, and protons are 27 in a neutral (cobalt-60).

To learn more about neutrons, protons, and electrons, visit: https://brainly.com/question/11691497

#SPJ4

The experiment described in the question given above supports the law of conservation of mass.

In chemistry, decomposition may be defined as a type of chemical reaction through which one reactant molecule significantly breaks down into two or more product molecules.

The same concept is applied in the question as well where the heating of mercuric oxide produces mercury and oxygen. According to the question, the mass of the reactant is equal to 2.16g, while the mass of the product is equal to 2.00 g plus 0.16 g which is togetherly 2.16 g.

Therefore, the experiment described in the question given above supports the law of conservation of mass.

To learn more about the Law of conservation of mass, refer to the link:

https://brainly.com/question/19038178

#SPJ4

Proton a couples to proton b. proton a possesses a j-value of 3.0 Hz. the j-value proton b possesses to be 3.0hz.

A proton contains two up quarks and one down quark. A neutron contains one up quark and two down quarks. The core is held together by one of four fundamental forces, the "strong nuclear force" (gravitational and electromagnetic forces are the other two). Heavy atoms tend to have more neutrons than protons, but the number of electrons in the atom is always equal to the number of protons. Therefore, the atom as a whole is electrically neutral.

There are two types of protons and neutrons: up quarks and down quarks. Each up quark has a +2/3 charge. Each down quark has a charge of -1/3. The sum of the charges of the quarks that make up the nuclear particle determines its charge.

Learn more about proton  here

https://brainly.com/question/1805828

#SPJ4

Sodium and chlorine are the two reactants and sodium chloride is the product.

Therefore, sodium and chlorine are reactants whereas sodium chloride is the product.

Learn more about chemical reactions:

https://brainly.com/question/11231920

#SPJ9

We emphasize the valence electrons in an atom when discussing atomic properties, as they are most accessible to other atoms.

The valence electrons are the electrons that are present in the outer shell of the atoms. These electrons are free for making bonds with the electrons of other atoms.

Electrons are joined with other electrons to make a compound. These electrons are shared by or gained by other atoms.

Thus, when discussing atomic qualities, we focus on the valence electrons in an atom since they are the most receptive to other atoms.

To learn more about valence electrons, refer to the link:

https://brainly.com/question/13993867

#SPJ4

According to Bohr's model, electron emit electromagnetic radiation when  an electron moves from the higher energy orbit to the lower energy orbit of an atom.

Niels Bohr (1885–1962) proposed a model for the hydrogen atom that explained its atomic emission spectrum.

According to the Bohr model of the atom:

1. Energy levels of electrons are discrete (certain discrete values of energy), that is why hydrogen shows discrete, bright, colored lines.

2. Electrons orbit the nucleus in orbits that have a set size and energy.

3. Electrons can jump from one energy level to another, absorbing or emitting electromagnetic radiation with a frequency ν (energy difference of the levels).

More about Bohr's model: brainly.com/question/18002213

#SPJ4

The action potentials of myocardial autorhythmic cells, are due to a combination of increasing Na⁺ and Ca²⁺      influx       and decreasing K⁺

    efflux      .

The autorythmic cells are concentrated in many areas such as:

Sinoatrial (SA) node which is located in the upper wall of the right atrium (auricle). It initiates the cardiac cycle by generating an action potential spreading throughout both atrium via gap junctions of the cardiac muscle fibers.

These autorhythmic cells have unique ability to depolarize spontaneously, which results in a pacemaker potential.  Channels of cardiac autorhythmic cells are responsible for the electrical signal that triggers heart contraction.

Autorhythmic cells begin depolarizing due to a slow continuous influx of Na⁺ and Ca²⁺, and a reduced efflux of K⁺.

Several protein channels are embedded in the plasma membrane of an autorhythmic cell that allows ions to move in and out of the cell. These are important for generating action potential.

To learn more about autorhythmic cells,

https://brainly.com/question/15517377

#SPJ4

The correct answer is 0.15.

We are aware that there is 0.05 mol of an unidentified hydrocarbon we will refer to as "X" and that its burning produces 6.6 g of carbon dioxide and 3.6 g of water.

These quantities might be converted to moles by applying the following formula:

amount= mass/ relative atomic mass

Thus, the following equation may be written for H2O: moles = 3.6 / 18 = 0.2 and for CO2: moles = 6.6 / 44 = 0.15.

0.05X + x'O2 = 0.15CO2 + 0.2H2O

This may be made simpler by dividing through by 0.05 (this step is likely to be the most helpful to you), resulting in:

1 x + x O2 = 3 co2 + 4 H2O

The hydrocarbon must have been the source of all the carbon in the carbon dioxide and all the hydrogen in the water.

Accordingly, 4 x 2 = 8 moles of H and 3 x 1 = 3 moles of C.

There are 3/1 = 3 Cs and 8/1 = 8 Hs in one X molecule.

This clearly identifies C3H8 or propane as the hydrocarbon X (dividing by 1 seems unnecessary, but it illustrates the process to use if there were more than one mol of X in the first equation).

To learn more about number of moles of carbon dioxide refer the link:

https://brainly.com/question/12723070

#SPJ9

The 14.1 ml solution has a density of 2.1365 g/ml.

Density is defined as the ratio between the mass of a substance and the volume it occupies. Denoted by ρ, density is mass per unit volume and the formula is given below:

ρ =  mass / volume

To solve for the density of a mixture or solution of two substances with different densities, the mass and volume of each substance must be known, as:

ρ mix = (M1 + M2) / (V1 + V2)

The volume and densities of the two given substances are known and can be used to solve for the unknown mass of each substance.

M1 = ρ x V1

M1 = 1.492 g/ml x 7.60 ml

M1 = 11.3392 g

M2 = ρ x V2

M2 = 2.890 g/ml x 6.50 ml

M1 = 18.785 g

Solving for the density of the mixture,

ρ mix = (M1 + M2) / (V1 + V2)

ρ mix = (11.3392 g + 18.785 g) / (7.60 ml + 6.50 ml)

ρ mix = 30.1242 g / 14.1 ml

ρ mix = 2.1365 g/ml

To learn more about density of mixtures: https://brainly.com/question/28037379

#SPJ4

When NAD becomes NADH, it is being reduced and gaining chemical energy.

Nicotinamide adenine dinucleotide (NAD), a coenzyme, can exist in two forms, NAD⁺ (oxidized) and NADH (reduced form).

Electrons and protons released in catabolism reactions are attached to NAD⁺. The conversion of NAD⁺ to NADH is important reaction for production of ATP during the cellular respiration.

Reduction is lowering oxidation number because element, ion or compound gain electrons.

Chemical equation for reaction of reduction of NAD⁺ (see picture below):

NAD⁺ + 2e⁻ + H⁺ → NADH

Nicotinamide adenine dinucleotide (NAD) is made of two nucleosides joined by pyrophosphate.

More about reduction :brainly.com/question/25334331

#SPJ4

The absolute error that could be expected when measuring the half-life of radon-220 is 0.416 s

The following data were obtained from the question:

We can obtaine the absolute error as illustrated below:

Percentage error = (Absolute error / Actaul measurement) × 100

0.8% = Absolute error / 52

0.008 = Absolute error / 52

Cross multiply

Absolute error = 0.008 ×52

Absolute error = 0.416 s

Thus, the absolute error in measuring the half-life is 0.416 s

Learn more about error:

https://brainly.com/question/24202332

#SPJ1

Answer:

Carboxylic acid group

Explanation:

Carboxylic acid and amine groups form the basis of an amino acid.  One group reacts with the other group on a neighboring amino acid to form the peptide bond, with the release of a water molecule.

The reaction that demonstrates a chemical change is iron (Fe) reacting to water((H,O)) and oxygen(O) to form iron oxide(Fe2Og). That is option B.

A chemical change is defined as the change that occurs when two substances reacts or combines to form an entirely new product.

The following are the features that shows that a chemical change has taken place. They include:

When the above signs are seems there is every reason to accept the fact that a chemical change has occurred in the chemical reaction that took place.

From the chosen option, the reactants and product of the chemical reaction are:

Iron (Fe) + water (H2O) --> iron oxide(Fe2Og)

This reaction is a chemical reaction as the product formed leads to a colour change known as rust.

Learn more about chemical change here:

https://brainly.com/question/19794032

#SPJ1

The peptide bond is broken by the hydrolysis of water. The hydrogen ion of water goes to the -NH end (shown to the right of bond C) and the hydroxyl Ion of water goes to the -CO ends (shown to the left of bond C), resulting in the breakdown of peptide Bond and formation of individual amino acid.

The reaction of water with another compound forms two or more products. Some examples of hydrolysis include dissolving salts of weak acids or weak bases in water or dissolving sulfuric acid in water to form hydronium and bisulfate compounds.

The difference between hydration and hydrolysis is that hydrolysis is the process of breaking a bond with water whereas hydration is defined as an electrophilic addition reaction without breaking the original molecule. During hydration, water molecules are added to the substance. A chemical decomposition process that involves breaking bonds and adding hydrogen cations and hydroxide anions of water.

Learn more about hydrolysis here

https://brainly.com/question/4352413

#SPJ4

There are 3 experiments which helps to under water evaporation system.

Learn more about Evaporation here:

https://brainly.com/question/24258

#SPJ9

A solution of known concentration that is slowly added to a solution of unknown concentration is called titrant.

Titration is the steady addition of a known concentration solution (called a titrant) to a known volume of an unknown concentration solution until the reaction approaches neutralization, which is sometimes indicated by a color change.

Until the reaction is complete, the analyte (the unknown solution) is normally added in a known amount to the titrant (the known solution) through a buret. Knowing the volume of titrant added allows the concentration of the unknown to be calculated. An indicator is often used to indicate the reaction's endpoint or end of reaction.

Therefore, titration is a technique used to determine the concentration of an unknown solution.

Read more about Titration:

https://brainly.com/question/16254547

#SPJ4

Answer: 27.69 mL^3

Explanation:

32.5 g * 0.852 g/mL=

32.5*0.852=27.69 mL^3       ==>Volume is expressed in units cubed.