The activity of a radioactive sample decays exponentially with time, and the half-life is the time it takes for the activity to decrease to half of its original value.
If the half-life of a radioactive element is T years, it will take 2T years for the activity to decrease to 25% of its original value, 3T years to decrease to 12.5% of its original value, and so on.
To calculate how many years it will take for the activity to decrease to a certain percentage of the original value, one can use the formula A=A0(0.5)^(t/T), where A is the activity at time t, A0 is the initial activity, and T is the half-life. Solving for t, we get t = T log₂ (A0/A), where log₂ is the logarithm to the base 2.
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An intermetallic compound is found in the magnesium–gallium system that has a composition of 41. 1 wt% mg–58. 9 wt% ga. Specify the formula for this compound.
The formula of the compound will be [tex]Mg_2Ga[/tex]
Empirical formula of compoundsThe compound contains magnesium and gallium. The symbol and magnesium and gallium is Mg and Ga respectively.
Magnesium content is 41.1%
Gallium content is 58.9%
First, find the number of moles of each element in the compound by dividing their percentage compositions with their respective molar weights.
Mg = 41.1/24.505 =1.6772
Ga = 58.9/69.723 = 0.8448
Next, divide each number of moles by the smallest number of moles.
Mg = 1.6772/0.8448 = 2
Ga = 0.8448/0.8448 = 1
Thus, the formula of the compound is [tex]Mg_2Ga[/tex]
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Hard-boiled eggs are made by placing eggs in boiling water until their whites and yolks solidify. Why does hard-boiling an egg take longer at high altitude than at sea level
Hard-boiled eggs are made by placing eggs in boiling water until their whites and yolks solidify. Hard-boiling an egg take longer at high altitude than at sea level because the high altitude lowers the boiling point of the egg.
Why do eggs turn hard when we boil them ?Hard-boiling an egg take longer at high altitude than at sea level because the high altitude lowers the boiling point of the egg. It takes longer for the water to reach 100°C.
Hard boiling an egg is a chemical change or physical change ?Hard boiling egg is a chemical change because the egg cannot back into its original form.
Chemical change are those changes in which substance changes chemical composition. These changes are permanent changes.
Thus from the above conclusion we can say that Hard-boiled eggs are made by placing eggs in boiling water until their whites and yolks solidify. Hard-boiling an egg take longer at high altitude than at sea level because the high altitude lowers the boiling point of the egg.
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The table shows columns that brenda uses for her notes on the properties of elements. her notes state that some elements can react to form basic compounds. a 3-column table with 2 rows. the first row has entries metals, metalloids, nonmetals. the second row has entries nothing, nothing, nothing. where should brenda place this property in her table? only in the column for metalloids only in the column for nonmetals in the columns for metalloids and for nonmetals in the columns for metals and for metalloids
The element should be placed in the column for metalloids. Option A
What is the property of metals?We know that the properties of metals can be used to identify an unknown substances as a metal. We know that metals are able to react with acids to liberate the metal salt and hydrogen gas. Metals do not react with bases because they can not accept electrons.
Metalloids are generally amphoteric in nature. They can react with both the acid and the basses to form compounds. The nonmetals do not react with acid or base.
Looking at the result, we are told that the entry in the second row have the entries nothing, nothing, nothing. If this is the outcome, then it follows that the element should be placed in the column for metalloids.
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Answer: A
Explanation:
3 A+B 2C+D
What is the percent yield of the reaction if 7.00 mol of A actually formed 1.00 mol of
C?
Answer:
Percent Yield = 21.4% C
Explanation:
The actual yield is the value that was produced after conducting an experiment. The theoretical yield is the value calculated using the balanced chemical equation.
To find the percent yield, you need to (1) convert moles A to moles C (via the mole-to-mole ratio from equation coefficients) and then (2) calculate the percent yield. It is important to arrange the ratios in a way that allows for the cancellation of units. The final answer should have 3 sig figs to match the sig figs of the values given.
3 A + B -----> 2 C + D
^ ^
7.00 moles A 2 moles C
--------------------- x ---------------------- = 4.67 moles C
3 moles A
Actual Yield
Percent Yield = ------------------------------ x 100%
Theoretical Yield
1.00 moles C
Percent Yield = ------------------------- x 100%
4.67 moles C
Percent Yield = 21.4% C
(iii) Calculate the volume of carbon dioxide at room temperature
and pressure that can be obtained from 30.0 g of glucose.
The combustion of 30.0 g of glucose at room temperature and pressure produces 24.0 L of carbon dioxide.
What is combustion?It is a reaction in which a substance burns with oxygen to form carbon dioxide and water.
Let's consider the combustion of glucose.
C₆H₁₂O₆ + 6 O₂ ⇒ 6 CO₂ + 6 H₂O
First, let's convert 30.0 g of glucose to moles using its molar mass.
30.0 g × 1 mol/180.16 g = 0.167 mol
The molar ratio of C₆H₁₂O₆ to CO₂ is 1:6. The moles of carbon dioxide produced are:
0.167 mol Glucose × (6 mol CO₂/1 mol Glucose) = 1.00 mol CO₂
1 mol of an ideal gas at room temperature and pressure occupies 24.0 L.
The combustion of 30.0 g of glucose at room temperature and pressure produces 24.0 L of carbon dioxide.
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Nal+ Pb(SO4)2
→> products and reaction type
The reaction is based on law of conservation of mass.
The balanced chemical equation is
[tex]$4 \mathrm{NaI}+\mathrm{Pb}\left(\mathrm{SO}_{4}\right)_{2} \rightarrow \mathrm{PbI}_{4}+2 \mathrm{Na}_{2} \mathrm{SO}_{4}$[/tex]
What is law of conservation of mass?Every balanced chemical equation follows the direction of conservation of mass. This law states that mass can neither be completed nor can be destroyed but it can only be transformed from one condition to another form. This law likewise states that the total number of individual atoms on the reactant side must be comparable to the total number of individual atoms on the product side.
The Law of Conservation of Mass holds because naturally occurring elements are stable under the conditions located on the surface of the Earth. Most elements come from fusion reactions found only in stars or supernovae. Consequently, in the ordinary world of Earth, from the peak of the highest mountain to the depths of the deepest ocean, atoms are not transformed into other elements during chemical reactions. Because of this, individual atoms that make up living and nonliving subjects are very old and each atom have a history. An individual atom of a biologically essential element, such as carbon, may have expended 65 million years buried as coal before standing burned in a control plant, followed by two decades in Earth's environment before being disbanded in the ocean,To learn more about law of conservation of mass, refer:
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How many moles of sucrose are in 5.25x10^29 sucrose molecules?
Answer:
8.72×10^5
Explanation:
Answered it in the comments! ^^
Cabbage juice indicator solutions can show pH values from acidic to basic.
Which color represents the most basic solution?
Which color represents the most acidic solution?
Which color represents a neutral solution?
More acid solution has red colour, more basic solution has purple colour whereas neutral solution has green colour.
Which color represents the most acidic solution?As the solution becomes more acidic, the color of the solution changes from green toward red.
Which color represents the most basic solution?As the solution becomes more basic, the color changes of the solution from green toward purple.
Which color represents a neutral solution?Green color of the solution represents a neutral solution having pH 7.
So we can conclude that More acid solution has red colour, more basic solution has purple colour whereas neutral solution has green colour.
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When limestone is decomposed at high temperature and the residue is treated with water, the compound that is formed is
The compound that is formed is calcium hydroxide.
Preparation of calcium hydroxideWhen limestone is decomposed at a high temperature, calcium oxide is formed as the residue.
[tex]CaCO_3 --- > CaO + CO_2[/tex]
When the calcium oxide residue is treated with water, a calcium hydroxide solution is formed.
[tex]CaO + H_2O -- > Ca(OH)_2[/tex]
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129) Which of the following metals have the highest atomic mass?
A) Copper
B) Gold
C) Iron
D) Platinum
130) What does the atomic number of an element represent in an neutral atom?
A) Number of electrons and protons.
B) Number of electrons and neutrons.
C) Number of protons and neutrons.
D) Does not have a specific representation.
Answer:
B) Gold
A) Number of electrons and protons.
Explanation:
Atomic Masses (from periodic table):
----> Copper (Cu): 63.546 g/mol
----> Gold (Au): 196.97 g/mol
----> Iron (Fe): 55.845 g/mol
----> Platinum (Pt): 195.08 g/mol
The atomic number represents the number of protons. Neutral atoms have the same number of protons as electrons. The mass number represents the number of protons and neutrons.
Calculate the pH if the [H^+] = 9.71 ×
10^-8
Answer:
pH = 7.01
Explanation:
The pH can be calculated using the formula:
pH = -log[H⁺]
In this formula, [H⁺] represents the concentration of H⁺. Since you have been given this value, you can easily find the pH.
pH = -log[H⁺]
pH = -log[9.71 x 10⁻⁸]
pH = 7.01
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What can be done to double the power output of an object?
Neither of these
Both of these
Take half the time to do the work
Double the work done by the object
93.4 g of a metal is heated to 85.0 C in a hot water bath, then dropped into a calorimeter containing 342 ml of water
The specific heat capacity of the metal is determined as 0.76 J/g⁰C.
Mass of the watermass = density x volume
mass = 342 ml x 1 g/ml = 342 g
Specific heat capacity of the metalApply the law of conservation of energy;
Heat lost by the metal = Heat gained by the calorimeter + heat gained by water
(93.4)(85 - 29.3)c = (8.29)(29.3) + (342)(4.186)(29.3 - 26.7)
5,202.38c = 3,965.088
c = 3,965.088/5,202.38
c = 0.76 J/g⁰C
Thus, the specific heat capacity of the metal is determined as 0.76 J/g⁰C.
The complete question is below;
93.4 g of a metal is heated to 85.0 C in a hot water bath, then dropped into a calorimeter containing 342 ml of water (d 1.00 g/mL) at 26.7 . The equilibrium temperature was found to be 29.3 C. Calculate the specific heat of the metal with proper units. (C.cal 8.29 J/c)
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The study of the structure of matter and the composition of substance, their properties, and their chemical reactions is called:
Answer: chemistry
Explanation: see definition on wikipedia.
What could the fourth quantum number of a 3p3 electron be?
A. ms=-1/2
B. ms=-1
C. ms=+1
D. ms=0
QUICK PLEASE
9. What is the final concentration when 420 mL of a 12.0 mol/L sodium hydroxide solution is diluted to 2.0 L?
Show your work and explain each step.
Answer: 2.52 M
Explanation:
The product of molarity (moles/litre) and volume in litres yields moles, and the numbers of moles in two solutions means dilute and concentrated are equal, which is expressed by the following equation:
[tex]M_1V_1=M_2V_2[/tex]
[tex]$$Given that\\M $1=12.0 \mathrm{M}$ or mole $/ \mathrm{L}$\\$\mathrm{V} 1=420 \mathrm{ml}$\\$\mathrm{M} 2=$ ?\\$\mathrm{V} 2=2.0 \mathrm{~L}$ or $2000 \mathrm{ml}$\\\\$\mathrm{M} 1 \mathrm{~V} 1=\mathrm{M} 2 \mathrm{~V} 2$\\$\mathrm{M} 2=\mathrm{M} 1 \mathrm{~V} 1 / \mathrm{V} 2$\\$=12.0 * 420 / 2000$\\$=2.52 \ \mathrm{M}$[/tex]
In sharp contrast to elimination reactions, addition reactions are generally favored at ______________________, because ________ is more likely to be negative at such temperatures.
In sharp contrast to elimination reactions, addition reactions are generally favored at low temperature, because enthalpy term is more likely to be negative at such temperatures.
What is Addition Reaction ?An addition reaction is an organic reaction occur when two or more molecules combine to form a larger molecule without the loss of any atoms present in reactant. Addition reaction is favored at low temperature.
What is Elimination Reaction ?Elimination reaction is a type of organic reaction where many atoms either in groups or pairs are removed from a molecule. Elimination reaction is favored at high temperature.
Thus from the above conclusion we can say that In sharp contrast to elimination reactions, addition reactions are generally favored at low temperature, because enthalpy term is more likely to be negative at such temperatures.
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A company sells a natural medicine with plant ingredients to help treat dementia, a disease in which people have a hard time remembering things. the natural ingredients in the medicine are most likely from which type of plant?
The type of plant should be ginkgo.
Ginkgo biloba is a popular herbal supplement used to improve memory and prevent dementia, presumably due to its antioxidant properties or anti-amyloid aggregation effects.
What is Dementia?Dementia is a term used to describe when a person's loss of certain behavioral abilities, such as remembering, thinking, and reasoning, interferes with their daily activities and life.
Dementia occurs when neurons in the brain stop functioning, lose their ability to communicate with other cells in the brain, and die. When people develop dementia, they may have problems with a variety of cognitive functions.
What Are Ginkgo Trees Used For?Aside from its decorative aspects, ginkgo biloba is a medical herb with numerous benefits. The tree is frequently used to treat a variety of ailments, including:
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Answer:
What is your question?
Explanation:
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Answer:
Stan TXT
Explanation:
because they are amazing
Which of these is the byproduct of fuel combustion that may result in death if such combustion equipment is not properly vented.
a. radon
b. lead
c. oxygen
d. carbon monoxide
Carbon monoxide is the byproduct of fuel combustion that may result in death if such combustion equipment is not properly vented and is denoted as option D.
What is Carbon monoxide?This is a compound which is derived from the combustion of carbon in insufficient supply of oxygen. Carbon monoxide when inhaled replaces the oxygen content in the body which is dangerous because oxygen is needed for the survival of the cells of the body.
The carbon monoxide is usually formed when there is no properly vent thereby resulting in insufficient supply of air. This therefore results in its presence in the body results in the death of cells of the body system.
This is therefore the reason why carbon monoxide was chosen as the most appropriate choice.
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When you are taking a test, you are awake and alert. this means that your brain is currently generating _____.
a. alpha wave
b. beta wave
c. theta wave
d. delta wave
When you are taking a test, you are awake and alert, which means that your brain is currently generating beta waves (Option b).
What are beta waves?The beta waves are a special type of brain waves observed by using electromagnetic devices (especially in physiology).
This type of waves are dominant during conscious thought as well as during cognitive logical thinking processes.
In conclusion, when you are taking a test, you are awake and alert, which means that your brain is currently generating beta waves (Option b).
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Thyroid hormone contains the mineral thyroid hormone contains the ________.
i. mineral iodine.
ii. sodium.
iii. iron.
iv. zinc.
v. thallium.
Thyroid hormone contains the mineral iodine (option I). Details about thyroid hormone can be found below.
What is the thyroid hormone?Thyroid hormone is the hormone produced by the thyroid gland of the body, which is a large butterfly-shaped endocrine gland situated on the front of the neck that produces various hormones.
The thyroid hormone is responsible for regulating metabolism, which controls the amount of calories burnt in a day.
One of the major minerals found in the thyroid is iodine. The thyroid gland absorbs iodine from the bloodstream, and then stores it to aid in the production of thyroid hormones.
Therefore, the thyroid hormone contains the mineral iodine.
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________ are weak bonds that are not strong enough to hold atoms together to form molecules but are strong enough to form bonds within and around large molecules.
Hydrogen bonds are weak bonds that are not strong enough to hold atoms together to form molecules but are strong enough to form bonds within and around large molecules.
The hydrogen bond is weak bond.The hydrogen bond is electrostatic force of attraction between hydrogen atom and more electronegative atoms or group ( like Florine , oxygen or nitrogen) which is contently bonded.The hydrogen bond is occur in polar , contently bond atoms in different molecules.Example is H-O-H or [tex]NH_{3}[/tex]The positively charged hydrogen side of one water molecule is bond with negatively charged oxygen side of another molecule.learn about Hydrogen bond
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What are the standard temperature and pressure conditions enthalpy is usually measured under?
A. 1 kPa and 273 K
B. 100 kPa and 298 K
OC. 298 kPa and 100 K
D. 1 kPa and 100 K
Reset Selection
The standard temperature and pressure conditions enthalpy is usually measured under are 1kPa and 273K (option A).
What is enthalpy?Enthalpy in thermodynamics is a measure of the heat content of a chemical or physical system.
Enthalpy is the sum of the internal energy and pressure times volume It can be calculated using the following formula:
H = E + P V
Where;
H = Enthalpy
E = internal energy
P = pressure
V = volume
However, the enthalpy of a substance is usually measured under standard temperature and pressure.
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A bottle of Nitroglycerin has the labeled strength of l/200 grains. What would this strength be in milligrams
strength in milligrams is 0.3mg
What is Strength?Mass of the solute in grams/Volume of the solution in litres equals the strength of the solution. The overall formula must be multiplied by 1000 if the volume is measured in millilitres (mL). The concentration of the solution, measured in grammes per litre, can be used to determine the solution's strength.
Molarity - The moles of solute per litre of solution is measured as molarity. For instance, when table salt is dissolved in water, water serves as both the solution and the solute. Sodium chloride weights 58.44 grammes per mole. One molar solution, or 1M, is created by dissolving 58.44 grammes of sodium chloride in one litre of water.
Relation between Molarity and Strength?
The volume of solute in one litre of a solution determines its strength. As a result, a solution's strength is calculated by multiplying its molecular mass by its molarity.
1 grain = 64.8 milligrams.
1/200 grains = 64.8/200
= 0.3mg
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A positive correlation ______ a causal link, and a negative correlation ______ a causal link.
A. does not necessarily indicate, does not necessarily indicate
B. does not necessarily indicate, always indicates
C. always indicates, does not necessarily indicate
D. always indicates, always indicates
A positive correlation does not necessarily indicate a causal link, and a negative correlation does not necessarily indicate a causal link. Option A
What is correlation?In research, correlation often indicates that some kind of relationship does exist between the variables. This does not actually mean causation. The correlation could be positive or negative.
It should be known that; a positive correlation does not necessarily indicate a causal link, and a negative correlation does not necessarily indicate a causal link. Option A
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Which one is the correct response?
Pollutants moving into underground water does not represent a social benefit of sustainable waste management.
What is sustainable waste management?It is the act of recycling wastes or reducing the amount of single-use products that end up as wastes in the environment.
By practicing sustainable waste management, fewer wastes are generated and lesser lands are used as landfills.
More lands become available and wastes are put to beneficial uses.
Pollutants moving into underground water is detrimental to the health of humans. Thus, it cannot represents one of the social benefits of sustainable waste management.
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The option that does not show the social benefit of sustainable waste management is leacha-te going into ground-water (Option D).
What is sustainable waste management?The term sustainable waste management has to do with the process in which pollutants are taken care of in a way that does not affect the environment.
The option that does not show the social benefit of sustainable waste management is leacha-te going into ground-water (Option D).
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Which is the site of gaseous exchange in the lungs?
Write the relationship between displacement, velocity and time?
Explanation:
1. The gaseous exchange in the lungs occurs in the alveoli. They are tiny air sacs at the end of the bronchioles (tiny branches of air tubes in the lungs). The alveoli are where the lungs and the blood exchange oxygen and carbon dioxide during the process of breathing in and breathing out.
Consider the chemical equilibrium of the reaction. NH4OH(aq) NH4 (aq) OH(aq) What will happen to the chemical equilibrium if NH4Cl is added to this solution
Answer:
hydrochloride acidic maby
Explanation:
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Sarif is performing a lab experiment, and one of the chemicals is labelled with the
following WHMIS pictogram.
Identify one hazard associated with a chemical that is labelled with this
pictogram. What is one precaution Sarif should take?
Answer:
Sarif should wear protective gloves, protective clothing.
Explanation: