A potassium-40 sample starts with 50 atoms, and 1.25 billion years later, there are 25 atoms. What is the half-life of potassium-40?

A. 2.5 billion years
B. 25 years
C. 40 years
D. 1.25 billion years

Answers

Answer 1
D. 1.25 billion years

Related Questions

A scientist distilled a quantity of water to use in an experiment. How much water did he collect if the condensation process released 9040 J of energy? H2O (l) -> H2O (g) ΔHv=2260 J/g a 0.0138 mol b 0.222 mol c 4.00 mol d 0.250 mol I really need the answer plz

Answers

Answer:

I know this is very late I am sorry, but

I believe your answer would be C) 4.00 mol.

Correct me if I am wrong.

Explanation:

9040 divided by 2260= 4

0.222 moles of water  released 9040 J of energy.

The heat of vaporization is defined as the heat required to convert 1 g of a substance from liquid to vapor. We are told that the heat of vaporization of water is 2260 J/g.

Hence;

1g of water releases  2260 J of heat

xg of water releases  9040 J of heat

x = 1g ×  9040 J /2260 J

x = 4 g

1 mole of water contains 18 g

x moles of water contains 4 g

x = 1 mole  × 4 g/18 g

x = 0.222 moles

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Does reactivity increase or decrease from left to right among elements in a period?

Answers

Period. As you move from either the left to the right, reactivity rises. Group reactivity diminishes from top to bottom.

As you move from left toward right across a period, responsiveness declines. Higher reactivity is caused by the ease with which electrons can be given or snatched away as you move further to the left as well as along the periodic chart.

This is because the size of both the atomic radius expands as the quantity of electronic energy does. reducing the attractiveness of other elements' valence electrons lowers reactivity.

It happens because there are more valence shells and less interaction among valence pairs of electrons. Consequently, the propensity to take electrons from some of the other atoms declines. Atoms get more electronegative as they move through a period.

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(Question) How many atoms are in 3 grams of Cu?
(20 points)

Answers

Answer: 2.85 x 10^22

Explanation:

We can use stoichiometry to convert grams to atoms.

*Important quantities*

Original amount of Copper: 3 grams

Molar mass of Copper: 63.5 grams

Avogadro's number: 6.022x10^23 atoms/formula units/molecules

Process - [tex]\frac{3gramCu}{1}[/tex]×[tex]\frac{1 mole Cu}{63.5 gCu}[/tex]×[tex]\frac{6.022x10x^{23} }{1 moleCu}[/tex] = 2.84503937×10^22

After taking sig figs into account, the answer needs to be rounded to 3 decimal places

Final answer: 2.85 x 10^22

Which component of the periodic table is needed to determine why KCl tastes like NaCl? A. Group B. Period C. Atomic Weight D. Atomic Number

Answers

Atomic Number of the periodic table is needed to determine why KCl tastes like NaCl.

What is the Periodic Table?

The Periodic Table is a tabular arrangement of the chemical elements organized by atomic number, electron configuration, and recurring chemical properties. It is one of the most important tools in chemistry, providing a useful framework to classify, systematize, and predict the properties of elements.

Atomic numbers are used to identify each element in the periodic table, and they are also used to determine the number of protons in the nucleus of an atom. The number of protons in an atom determines its chemical properties, and the similarity in the number of protons between two elements can explain why they have similar properties. In this case, the similarity in the atomic number of potassium (K, atomic number 19) and sodium (Na, atomic number 11) explains why the salts of both elements, potassium chloride (KCl) and sodium chloride (NaCl), taste the same.

Hence, Option D is correct.

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Iron objects such as storage tanks and underground pipelines can be protected from corrosion by connecting them through a wire to a piece of : Ag
Pb
Sn
Mg
Cu

Answers

Iron objects such as storage tanks and underground pipelines can be protected from corrosion by connecting them through a wire to a piece of Mg.

General corrosion happens when the majority or even all atoms on such a metal surface become oxidized, causing the surface to corrode completely. The majority of metals were easily oxidised, which means they frequently lose oxygen electrons (among other elements) in the air either in water. Oxygen joins with the metal to produce an oxide as it becomes reduced (gains electrons).

A refined metal usually transformed naturally by corrosion into a safer stable chemical form, including its oxide, hydroxide, and sulphide. By reacting chemically and/or electrochemically with their surroundings, materials slowly degrade. Additionally, it gradually eliminates the element using chemical processes.

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help help help help help helps​

Answers

Answer:

C may be the correct answer

Why are the elements in Groups 1 and 17 so reactive?

Answers

Fluorine as well as chlorine are among the substances in group 17. Alkali metals as well as hydrogen are both part of group 1 on the periodic table.

Group 1 elements were extremely reactive due to the fact that they only contain one valence electron. As just a result, atoms were only ever combined with some other elements present in nature.

Due to their size as well as low ionisation enthalpy, alkali metals were extremely reactive metals. Moving lower in the group causes them to become more reactive. Reactivity to air: These metals discolor when exposed to dry air because oxides create, which then react with moisture to generate hydroxides.

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How are the boiling point and freezing point of a solvent affected when a solute is added?
O Both the boiling point and the freezing point decrease.
O Both the boiling point and the freezing point increase.
O The boiling point increases, and the freezing point decreases.
O The boiling point decreases, and the freezing point increases.

Answers

Answer:

the boiling point increases and the freezing point decreases.

What particle limitation to the widespread of this reusable water bottles? Pls help someone

Answers

Answer: Plastic water bottles

Explanation:

If you use disposable water bottles, here are some important concerns you should know about how they’re made as well as the problems they cause for the planet, your health, and your wallet.

Classify the reaction in each of the following equations.

a. BaCl2 (aq) + K2CrO4 (aq) → BaCrO4 (s) + 2KCl(aq)


b. Si(s) + 2Cl2 (g) → SiCl4 (l)

Answers

Answer:

a) Double replacement

b) Synthesis

Explanation:

a) For A, we have two ionic reactants that form two ionic products, where the anion (or cation) is swapped. This is a characteristic of a double replacement reaction.

b) For B, two elements, this time two elements, react together to form one product that's unlike the reactants. This is a characteristic of a synthesis reaction.

PLEASE HELP
What is the difference between a soap an detergent?

1. Soaps have long hydrocarbon chains and detergents have long nitrogen chains,

2. Detergents contain carboxylic acid groups and soaps contain phosphoric acid groups.

3. Detergents have long hydrocarbon chains and soaps have long nitrogen chains.

4. Soaps contain salts and detergents contain sulfonic or phosphoric acid groups.

Answers

I think the answer should be 4 because detergents contain phosphoric acid

What is true about the nature of light?

Select all that apply.

Light behaves as a wave, which is shown when it is passes through slits and produces a diffraction pattern.

Light can be reflected in different colors seen by the human eye.

Light is composed of small lines of color called photons.

Light behaves as a particle, which is shown when it is shines on a metal and produces current.

Answers

I would say the first one

2 points of the water molecule are the paired ______ and _______ electrons from the oxygen atom and ________ electron from each H atom
The other 2 points of the water molecule are the paired _________ electrons of the oxygen atom.

I get what the question is asking and I know general idea of the answer. I just can't for the life of me figure out what exact wording I am supposed to use that will fit these blanks

Answers

To solve this we must be knowing each and every concept related to chemical Compound. Therefore, The other 2 points of the water  molecule are the paired two electrons from the oxygen atom and one electron from each H atom.

What is chemical Compound?

Chemical Compound is a combination of molecule, Molecule forms by combination of element and element forms by combination of atoms in fixed proportion.

There are two types of chemical compound one is covalent compound and other is ionic compound, covalent compound formed by sharing of electron and ionic compound formed by complete transfer of electron. The other 2 points of the water  molecule are the paired two electrons from the oxygen atom and one electron from each H atom.

Therefore, The other 2 points of the water  molecule are the paired two electrons from the oxygen atom and one electron from each H atom.

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The heat of vaporization for water is 40.7 kJ/mol. How much heat energy must 150.0 g of water absorb to boil away completely

Answers

The heat of vaporization for water is 40.7 kJ/mol. the heat energy must 150.0 g of water absorb to boil away completely is 6106 kJ.

The expression is given as :

q = m ΔH

where ,

q is heat energy

m is the mass

ΔH is the heat of the vaporization.

q = heat = ?

m = mass  = 150 g

ΔH = heat of vaporization = 40.7 kJ/mol

q = 150 × 40.7

q = 6106 kJ

Thus , if the heat of vaporization is 40.7 kJ/mol ,the heat energy required for 150 g of water absorb to boil away completely is 6106 kJ.

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List some Industrial plants and indicate the gaseous pollutants they emit​

Answers

Answer:

Sources of air pollutants from the industry include: power generation plant, boilers, bleaching plants and caustic soda/chlorine plant. Pollutants include particulate matter, chlorine, sulfur dioxides, hydrogen sulfides, carbon dioxide, carbon monoxides and nitrous oxides.

Prior to Thomson's discovery, the atom was thought to be indivisible. Explain the significance of Thomson's concept of the electron.

Answers

In 1897, J.J. Thomson's discovery of the electron was revolutionary.

What is thomson's concept?

Thomson's concept of the electron showed that the atom was not indivisible, but instead was composed of smaller particles. This discovery provided the first piece of evidence to support the atomic theory, which states that all matter is made up of atoms.

Thomson's concept of the electron also allowed scientists to understand the behaviour of electricity better. Electrons are negatively charged particles, and Thomson's discovery showed that electricity is a flow of electrons. This knowledge allowed scientists to create new technologies based on the understanding of electrons, such as computers and cell phones.

The significance of Thomson's concept of the electron can be summed up in three words: evidence, electricity, and technology. Thomson's discovery provided the first piece of evidence for the atomic theory, allowed for a better understanding of electricity, and paved the way for the creation of many new technologies.

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Entropy and the inefficiency of energy transfer are part of __________________. the first law of thermodynamics the second law of thermodynamics the third law of thermodynamics system resiliency feedback systems

Answers

Entropy and the inefficiency of energy transfer are part of the Second Law of Thermodynamics.

The first law of thermodynamics states that neither creation nor destruction of energy is possible. The universe becomes more entropic when a spontaneous process occurs, according to the second law of thermodynamics. Thermodynamics' third law: The entropy of a perfect crystal is 0 at absolute zero Kelvin. The overall entropy of a system may only ever increase or stay constant during spontaneous processes, according to the second law of thermodynamics. If the physical process is irreversible, the overall entropy of the system and its surroundings must increase. For a process to be irreversible, the final entropy needs to be higher than the starting entropy: Sf > Si (irreversible process). The overall entropy of a system and its surroundings can remain constant when a system is in thermodynamic equilibrium or undergoing a reversible process. The second law is sometimes known as the Law of Increased Entropy.

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yousab cycles at an average speed of 12 km/h. how far has he travelled if he cycles for 2 hours

Answers

Answer:

24 km

Explanation:

(12 km/hr)(2 hrs) = 24 km

If 6.00 L of 3.00 M HCl is added to 5.00 L of 2.00 M Ca(OH)2, which species will be the limiting reactant

Answers

HCl will be the limiting reactant for the above question

When HCl and Ca(OH)2 are mixed, they react to form water and calcium chloride (CaCl2) according to the following equation: HCl(aq) + Ca(OH)2(aq) -> CaCl2(aq) + 2H2O(l). To determine which species is the limiting reactant, we need to compare the amount of HCl and Ca(OH)2 present in the reaction.The number of moles of HCl present in the reaction is given by the equation n=CV, where n is the number of moles, C is the concentration of the solution and V is the volume. Hence  number of HCL moles is:

n = 3.00 M 6.00L = 18.0 moles The number of moles of Ca(OH)2 present in the reaction is given by the equation n=CV, where n is the number of moles, C is the concentration of the solution and V is the volume. So the number of moles of Ca(OH)2 is: n = 2.00 M 5.00L = 10.0 moles. The number of moles of HCl is greater than the number of moles of Ca(OH)2, so HCl will be the limiting reactant.

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Which of the following could account for the weakening of hurricanes when they reach the Atlantic Ocean? Ocean waters in the Atlantic . .

A.) decrease in temperature.
B.) increase in temperature.
C.) decrease in salinity.
D.) increase in salinity.

Answers

A decrease in temperature could account for the weakening of hurricanes when they reach the Atlantic Ocean. hence option A is the correct answer.

How is Hurricane formed?

There must be warm ocean water and wet, humid air in the area for one to form. When humid air flows upward at a low-pressure zone over warm ocean water, water is released from the air, resulting in storm clouds. The air in a hurricane rotates as it rises.

Hurricanes begin with the evaporation of warm seawater, which causes water to be pumped into the lower atmosphere. When converging winds collide and turn upwards, this humid air is pulled aloft.

Hurricanes arise when warm, moist air rises over sea. Cooler air replaces the rising air. Large clouds and thunderstorms continue to form as a result of this process. Because of the Coriolis Effect, these thunderstorms continue to expand and begin to rotate.

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2
Select the correct answer from each drop-down menu.
How are real gases different from ideal gases?
Real gases differ from ideal gases because in a real gas,....

Answers

Answer:

Real gases particles are smaller than ideal gases

This energy diagram shows the allowed energy levels of an electron in a certain atom or molecule: energy Use this diagram to complete the table below. Which is the ground state? (pick one) How many excited states are there? How many lines are in the absorption line spectrum? Which transition causes the absorption line at the shortest wavelength? Which transition causes the absorption line at the longest wavelength?

Answers

The transition causing the absorption line at the longest wavelength is the transition from -2 to +2.

Ground State: -2

Number of Excited States: 4

Number of Lines in the Absorption Line Spectrum: 8

Transition Causing Absorption Line at Shortest Wavelength: -3 to -2

Transition Causing Absorption Line at Longest Wavelength: -2 to +2

The ground state is the state at the bottom of the diagram, which is -2.

There are 4 excited states, which are -3, -2, +1, and +2.

There are 8 lines in the absorption line spectrum, which are the 4 transitions from the ground state to the excited states, and the 4 transitions from the excited states back to the ground state.

The transition causing the absorption line at the shortest wavelength is the transition from -3 to -2.

The transition causing the absorption line at the longest wavelength is the transition from -2 to +2.

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SEP Compare Data Look at the data in Figure 2. Which is the most
electronegative
atom? Which is the least?

Answers

The most electronegative atom is Flourine and the least is Hydrogen

How is fluorine the one with most electronegative atom?

The attached image indicates how the highly electronegative Fluorine atom takes away most of the electron density (red-to-blue colored cloud) from a hydrogen–fluoride covalent bond.

An electronegative atom is an atom that has a tendency to attract electrons towards itself when it is part of a chemical bond. The most common example is the oxygen atom. The ability of an atom to attract electrons is known as its electronegativity.

The higher the electronegativity of an atom, the more it will pull electrons towards itself. The electronegativity of an atom is determined by its atomic number and the number of electrons in its outermost shell.

Therefore, the correct answer is as given above

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What is the molarity of a solution that contains 2.21 moles of MgBr2 in 2.93 L of solution?

Answers

Answer:

0.754M MgBr2

Explanation:

Molarity = Moles/Volume(liters)

2.21/2.93 = 0.754M MgBr2

How does glycolysis make 32 ATP?

Answers

Both anaerobic and aerobic conditions can result in glycolysis. Pyruvate joins the citric acid cycle under aerobic conditions and proceeds through oxidative phosphorylation, which results in the net synthesis of 32 ATP molecules.

What is an example of anaerobic activity?

Anaerobic exercises require small bursts of energy and are finished rapidly while exerting maximum effort. Examples include jumping, jogging, and hard weightlifting. Your breathing and heart rate alter as you engage in aerobic vs anaerobic activities. During aerobic workouts, oxygen is your major source of energy.

What exactly does it mean to be anaerobic?

Anaerobic means "without oxygen," whereas aerobic indicates the existence of oxygen. Both are important for your overall health since they put your body through different difficulties. Anaerobic exercise consists of short bursts of high-intensity activity that do not demand your body to consume oxygen as it would during cardio (or aerobic) exercise.

Here,

Glycolysis can occur under both anaerobic and aerobic settings. Under aerobic circumstances, pyruvate enters the citric acid cycle and goes through oxidative phosphorylation, resulting in the net production of 32 ATP molecules.

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Select the correct answer. which gas is the most abundant greenhouse gas?
a. ozone
b. chlorofluorocarbon
c. carbon dioxide
d. methane
e. water vapor

Answers

E) The most significant and prevalent greenhouse gas is water vapor. Ozone, carbon dioxide, methane, nitrous oxide, and other gases are also present.

Which major source of greenhouse gases is it?

Over the past 150 years, almost all of the rise in atmospheric greenhouse gases has been caused by human activities. Burning fossil fuels for transportation, electricity, and heating is the primary human activity in the United States that contributes to the emission of greenhouse gases.

Which four greenhouse gases have the greatest impact?

The greenhouse gases on Earth warm the planet by storing heat in the atmosphere. Carbon dioxide, methane, nitrous oxide, and water vapor—all of which are found naturally—as well as fluorinated gases—which are made—are the main gases that cause the greenhouse effect.

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Give three examples of fuels and briefly describe what they are used for in daily life

Answers

Examples: natural gas, coal, petroleum

Uses: Fuels are dense repositories of energy that are consumed to provide energy services such as heating, transportation and electrical generation. Even though most fuels ultimately get their energy from the sun (see energy conservation) they are usually considered to be a primary energy source.

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How many atoms are indicated by the prefixes for each of the following items. drag each item to the appropriate bin
tetrisdide montui donde bro utracondo chloride triponthou Decode 1 atom 2 atoms 3 atoms 4 stoms 5 atoms 6 atoms

Answers

The prefixes you provided do not correspond to any known chemical element or compound. The prefixes used in chemistry typically come from Greek or Latin and indicate the number of atoms present in a molecule of a certain element or compound.

For example, "mono-" indicates 1 atom, "di-" indicates 2 atoms, "tri-" indicates 3 atoms, "tetra-" indicates 4 atoms, and so on. prefixes let me know if you have any other question

Mono - 1 - montui, chloride

di - 2 atoms - donde

tri - 3 atoms - triponthou

tetra - 4 atoms - tetrisdide

utra - 5 atoms - utracondo are prefixes .

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What is the relative rate of diffusion of CH4 and NO2?

Answers

Answer:

=32×1632×√1632=34√2.

Explanation:

the diameter of a sodium atom, na, is larger than the diameter of a sodium ion, na , because the sodium ion has

Answers

Na+ has one fewer electron than Na, making it smaller and possessing a higher effective nuclear charge.

The fact that sodium ions have just two electron shells makes them smaller than sodium atoms for the main reason (the atom has three). Because they both have the same number of nucleons, the Na+ ion and Na atom have the same nuclear charge. Na+, on the other hand, has a smaller nuclear charge than Na because it has one fewer electron. Na+ is therefore smaller than Na because there is more attraction on the electrons that are already there. A sodium ion's size is smaller than that of a sodium atom.

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Read chapter 1, The Prison-Door, from The Scarlet Letter by Nathaniel Hawthorne and answer the question that follows.A throng of bearded men, in sad-colored garments and gray, steeple-crowned hats, intermixed with women, some wearing hoods, and others bareheaded, was assembled in front of a wooden edifice, the door of which was heavily timbered with oak, and studded with iron spikes.The founders of a new colony, whatever Utopia of human virtue and happiness they might originally project, have invariably recognized it among their earliest practical necessities to allot a portion of the virgin soil as a cemetery, and another portion as the site of a prison. 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