A sample of radioactive material starts with 80 grams. After 3 half-lives have passed, how much radioactive sample remains?
Answer:
I want to say 10 grams
Explanation:
80 grams is your start
and a half-life is half of that so...
half of 80 ( and or 80/2)
40 grams
then another half is...
half of 40 (and or 40/2)
20 grams
then another half-life is...
half of 20 (and or 20/2)
10 grams
That is 3 half-life of 80 grams
*becareful not to just divide 80 / 3 you will get 26.666 (repeating) that is incorrect
you want a half of a half of a half
An angle of refraction is the angle between the refracted ray and the
incident ray.
normal.
medium.
boundary.
Answer:
Normal
Explanation:
with the boundary, is a glancing angle
with the incident ray, is the field of view
Answer:
B. normal
Explanation:
Which best defines a service? a task that is performed in exchange for payment an object that is acquired a plan that is executed an image that is drawn
Answer:
a task that is performed for payment
Explanation:
all of the other answers do not pertain to the question
A service is best defined as a task that is performed in exchange for payment.
What is a task?A task is an activity that needs to be accomplished within a defined period of time or by a deadline to work towards work-related goals, usually done in exchange for payment.
Thus, we can conclude that, a service is best defined as a task that is performed in exchange for payment.
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Which one is true? Elements in the same row have the same number of:
Explanation:
Elements in same row (i.e, from left to right) have the same number of electron shells.
g In this equation stands for the Rydberg energy, and stands for the principal quantum number of the orbital that holds the electron. (You can find the value of the Rydberg energy using the Data button on the ALEKS toolbar.) Calculate the wavelength of the line in the emission line spectrum of hydrogen caused by the transition of the electron from an orbital with to an orbital with . Round your answer to significant digits.
The complete question is attached to this answer
Answer:
2.75 * 10^-5 m
Explanation:
The energy of the absorbed photon = ΔE
ΔE = - Ry (1/n^2 final - 1/n^2initial)
Given that Ry = 2.18 *10^-18 J
nfinal = 9
ninitial =8
ΔE = - 2.18 *10^-18 (1/9^2- 1/8^2)
ΔE = - 2.18 *10^-18 (0.0123 - 0.0156)
ΔE = 7.194 * 10^-21 J
But
ΔE =hc/λ
h = 6.6 *10^-34Js
c= 3 * 10^8 ms-1
λ= the unknown
λ= hc/ΔE
λ= 6.6 *10^-34 * 3 * 10^8/ 7.194 * 10^-21
λ= 2.75 * 10^-5 m
Name one way that the scientific community has honored Mendeleev’s contribution to science.
Answer:
Mendeleev's greatest contribution to science is certainly the Periodic Table of Elements, which says the properties of basic elements repeat periodically when they are arranged by their atomic number. He made the discovery in 1869 during his work on the award-winning textbook on chemistry basics.
Inventions: Periodic table, Pyrocollodion
Explanation:
*Hope this helps*
Answer:
Mendeleev's greatest contribution to science is certainly the Periodic Table of Elements, which says the properties of basic elements repeat periodically when they are arranged by their atomic number. He made the discovery in 1869 during his work on the award-winning textbook on chemistry basics.
Inventions: Periodic table, Pyrocollodion
Explanation:
How many moles are present in 2.126 g of H2O2 ?
Answer:
molecular weight of H2O2 or grams. This compound is also known as Hydrogen Peroxide. The SI base unit for amount of substance is the mole. 1 mole is equal to 1 moles H2O2, or 34.01468 grams.
1 grams H2O2 is equal to 0.029399071224542 mole.
1 grams H2O2 to mol = 0.0294 mol
10 grams H2O2 to mol = 0.29399 mol
20 grams H2O2 to mol = 0.58798 mol
30 grams H2O2 to mol = 0.88197 mol
40 grams H2O2 to mol = 1.17596 mol
50 grams H2O2 to mol = 1.46995 mol
100 grams H2O2 to mol = 2.93991 mol
200 grams H2O2 to mol = 5.87981 mol
There are 0.0625mol in 2.126 g of H2O2.
HOW TO CALCULATE MOLES:
The number of moles of a substance can be calculated by dividing the mass of the substance by its molar mass. That is;no. of moles (mol) = mass (g) ÷ molar mass (g/mol)According to this question, 2.126 g of H2O2 were given. The number of moles of H2O2 can be calculated as follows:Molar mass of H2O2 = 1(2) + 16(2)= 2 + 32
= 34g/mol
no. of moles = 2.126g ÷ 34g/molno. of moles = 0.0625molTherefore, there are 0.0625mol in 2.126 g of H2O2..Learn more at: https://brainly.com/question/21085277?referrer=searchResults
A sample is in the second half-life. What percent of the sample is stable at this point?
A. 12.5%
B. 25%
C. 50%
D. 75%
Answer:
75%
Explanation:
on edg :)
Bruh I hate science Pls help me
List 5 physical properties of matter.
What is a chemical property?
List 2 chemical properties.
What is the difference between chemical property and chemical change?
List 3 products that are the results of chemical reactions.
Answer:
1. The properties of matter include any traits that can be measured, such as an object's density, color, mass, volume, length, malleability, melting point, hardness, odor, temperature, and more.
2. A chemical property is a characteristic of a particular substance that can be observed in a chemical reaction.
3. Toxicity and acidity.
4. A chemical property describes the ability of a substance to undergo a specific chemical change. A chemical reaction is a process that occurs when one or more substances are changed into one or more new substances.
5. The five basic types of chemical reactions are combination, decomposition, single-replacement, double-replacement, and combustion. Analyzing the reactants and products of a given reaction will allow you to place it into one of these categories. Some reactions will fit into more than one category.
Hope this helps you~
Pieces of DNA that pass genetic traits from parent to offspring are what?
A. Heredity
B. Phenotype
C. Gene
D. Allele
Pieces of DNA that pass genetic traits from parent to offspring are called as gene.
What is DNA?DNA is a hereditary material which is present in human beings as well as all other living organisms. Every cell which is present in an organism's body has DNA which is the same. Most of the DNA is situated in the cell's nucleus and small amount of it can be found in the cell's mitochondria as well.
Information which is stored in DNA is stored as codes made up of four chemical bases namely, adenine, thymine , cytosine and guanine.Human DNA consists of 3 billion bases .The order of the bases determines information which is required for building and maintaining an organism.
DNA bases are capable of pairing up with each other. Adenine pairs with thymine and guanine pairs up with cytosine .Each base is also attached to a sugar molecule and a phosphate group. A base, phosphate sugar are together called as nucleotides.
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What else is produced when sodium carbonate decomposes?
Na2Co3 - Na2O+
Answer:When a single compound breaks down into two or more compounds or elements in a chemical reaction then it is known as decomposition reaction.
The chemical symbol for sodium carbonate is .
The decomposition of sodium carbonate is:
The decomposition of sodium bicarbonate, will result in the formation of sodium oxide, and carbon dioxide, .
Hence, carbon dioxide, will produce with sodium oxide, on decomposition of .
Explanation:Na2CO3 Na2O +CO2 CO2 is the answer
According to the collision theory, which is required for a high number of effective collisions? a very low amount of force from colliding molecules a very low amount of kinetic energy from colliding molecules molecular collisions that have very specific orientations molecular collisions with energy to overcome activation energy
Answer:
the answer is D
Explanation:
i answered c and got it wrong on edg... i hope this helps :)
According to the collision theory, molecular collisions that have very specific orientations are required for a high number of effective collisions.
What is collision theory?Collision theory is used to predict the rates of chemical reactions, particularly for gases.
Based on the collision theory, a high frequency of effective collision is dependent on the molecular collisions that have very specific orientations.
The collision theory suggests that for reactions to occur, there must collision between reacting particles.
The number of collision is dependent on the number of collision per unit time as well as fractions of effective collision.
To attain effective collision, colliding particles must be properly oriented to give the desired product.
Hence, option C is correct.
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find the number of hydrogen atoms of an alkyl group with 2 carbon atoms if n=2
Answer:
5
Explanation:
An alkyl group is a functional group that contains only hydrogen and carbon atoms. It has the general formula: CnH2n+1.
Since n=2, plug it into the formula.
C2H2(2)+1
=
C₂H₅
Hope that helps.
. A student adds 50 mL of Lead (II) Nitrate solution to 50 mL of potassium iodide. Each
solution is colorless, but when these two liquids are mixed, a yellow precipitate is
observed. What has most likely happened in the experiment?
Answer:
after the reaction between Lead (II) Nitrate solution and potassium iodide occur Lead(II) iodide was formed and it's yellow color.
Explanation:
Pb(NO3)2 + KI = KNO3 + PbI2
_____increases when a ball bounces up and decreases as ball does down. Answers choices. A.Thermal Energy. B. Kinetic Energy. C. Potential Energy. D. Heat
Answer:
C. potential energy
Explanation:
got 100 on edg
Rosie balanced the equation below with the lowest coefficients, however she made a mistake.
2 AgCl + 2 Mg(NO3)2 --> 1 AgNO3 + 2 MgCl2
What was her error and what should the correct answer be?
Answer:
2 AgCl + Mg(NO3)2 --> 2AgNO3 + MgCl2
Explanation:
This is balanced equation
PLEASE HELP WILL GIVE BRAINLIEST
Answer: B
We use stoichiometric amounts of P4 and PH3
NO.9) It's actual yield
Based on the chemical equation, use the drop-down menu to choose the coefficients that will balance the chemical equation:
(
)BaO2 + (
)H2SO4 → (
)H2O2 + (
)BaSO4
Answer:
1
1
1
1
Explanation:
the equation is balancing
Which electron dot diagram represents H2?
Answer:
H:H
Explanation:
Two models of the same compound are shown.
On the left labeled Model A 2 large overlapping black spheres with 3 small blue spheres overlapping the rear black sphere and 2 medium red spheres overlapping the front black sphere. One of the red spheres has a small blue sphere overlapping it. On the right labeled Model B 2 C's connected by a black line. The C on the left has 3 H's attached by 1 black line each and the C on the right has 2 Os attached to it. The top O is attached by 2 black lines and the bottom O by 1 black line. The bottom O also has an H attached to it by 1 black line.
In what way is Model A better than Model B?
Model A shows the types of elements in the compound, but Model B does not.
Model A shows the total number of atoms in the molecule, but Model B does not.
Model A shows the three-dimensional shape of the molecule, but Model B does not.
Model A shows the number of atoms of each element in the molecule, but Model B does not.
Answer: C. Model A shows the three-dimensional shape of the molecule, but Model B does not.
Explanation:
i took the test and it makes the most sence for the modeles.
Question 1 (3 points)
(01.01 LC)
Which of the following objects will exert the greatest gravitational force on a box, if the distance between them remains the same? (3 points)
Оа
2 kg mass
Ob
4 kg mass
Ос
6 kg mass
8 kg mass
The following objects will exert the greatest gravitational force on a box⇒ 8 kg mass
Further explanationGravity is a force that arises because of the attraction between objects with mass.
The magnitude of this attraction is proportional to the mass of the object.
The greater the mass of the object, the greater the gravitational force
Relationships can both be stated in
Newton's Gravity Law:
[tex]\rm F=G.\dfrac{m_1.m_2}{r^2}[/tex]
with F = gravitational force,
G = gravitational constant,
m1, m2 = mass of object,
r = distance between two objects.
The distance-r and mass of the box(m₁) are the same, then the largest object's mass (m₂)exerts a large gravitational force, because the gravitational force is directly proportional to the mass of the two objects
How many hydrogen molecules are needed to produce two H2O molecules
Answer:
There are 2 Hydrogen molecules in H2O
Explanation:
if you look at the symbol for Hydrogen (H) you see that there is a number beside it, to the right. That number shows how many molecules there are of that element.
(Sidenote: If there is no number there is only one molecule)
Hope this helped :)
Magnesium has a density of 1.738 g/cmº at 25°C. What is the mass of a block of
magnesium that has a volume of 743 cm??
Answer:
87.50g(1cm^3/1.1738g)=50.345 cm^3
Explanation:
volume units id in cubic centimeters
Amino acids are the building blocks of proteins. The simplest amino acid is glycine (H2NCH2COOH). Draw a Lewis structure for glycine. (Hint: The central atoms in the skeletal structure are nitrogen bonded to carbon, which is bonded to another carbon. The two oxygen atoms are bonded directly to the right-most carbon atom.) Draw the molecule by placing atoms on the grid and connecting them with bonds. Include all hydrogen atoms and nonbonding electrons.
Answer:
Explanation:
The lewis structure (indicating all the atoms and patterns provided as hint in the question) of glycine can be seen in the attachment below. While the chemical structure of glycine can be seen below
H
|
H₂N - C - C =O
| \
H OH
The structure (of glycine) above provides a "fair idea" of how the lewis structure will be.
Which of the following are examples of QUALITATIVE data? (seiect all that apply)
None these is qualitative data
The sound of a person's voice
The weight of person
The hair color of a person
The body temperature of a person
Answer:
The hair color of a person
Explanation:
The correct answer would be the hair color of a person.
Qualitative data are data that cannot be measured with any instrument but can only be used to characterize. Unlike quantitative data, these kinds of data can only be observed and recorded but cannot be assigned numerical values, except if coded.
The sound of a person's voice can be quantitative on one hand and qualitative on the other. The intensity of a sound can be measured using a decibel meter and quantitatively assigned a figure, whereas, the quality of the sound can only be characterized and not measured.
Both the weight and the body temperature of a person can be measured using a weighing balance and a thermometer respectively and hence, are considered to be quantitative data when collected.
The color of the hair of a person cannot be measured but can only be observed and characterized. Hence, hair color data constitute qualitative data.
Answer:
hair color
Explanation:
HELPPPPPP
is this
1:conduction
2:radiation
3:convection
Answer:
Radiation
Explanation:
Sun rays shine on earth. Thats radiation.
Gold III Bromide is heated in a flask filled with chlorine gas.
The reactants of this reaction are:
I
The type of reaction is:
The products of this reaction are:
Answer:
detail is given below.
Explanation:
Chemical equation:
AuBr₃ + Cl₂ → AuCl₃ + Br₂
Balanced chemical equation:
2AuBr₃ + 3Cl₂ → 2AuCl₃ + 3Br₂
The reactants of this chemical reaction are,
AuBr₃
Cl₂
The product of this chemical reaction is,
AuCl₃
Br₂
Reaction type:
The reaction type is single replacement reaction.
Single replacement:
It is the reaction in which one elements replace the other element in compound.
AB + C → AC + B
In a similar way chlorine replace the bromine and form gold(III) chloride and bromine gas.
The Lewis diagram for BH2 is:
[H-B-H]-
The electron- pair geometry around the B atom in BH2 is:__________.
There are______lone pair(s) around the central atom, so the geometry of BH2 is________ .
Answer:
Electron pair geometry- trigonal planar
There is one lone pair around the boron atom
The geometry of BH2 is bent
Explanation:
The valence shell electron pair repulsion theory offers a frame work for determining the shape of molecules based on the number of electron pairs of the valence shell of the central atom in the molecule.
In BH2-, the central atom is boron. There is a lone pair on boron. Owing to the lone pair on boron, the molecular geometry of BH2 is bent.
The geometry of the electron pair around the Boron atom in [tex]BH_2[/tex] is called the trigonal planar. In this case, there is a pair of isolated electrons around Boron, which is the central atom, allowing the [tex]BH2[/tex] molecule to have a folded geometry.
We can arrive at this answer because:
Boron is an element that has three electrons in its valence layer.With this, we can find out that it can make three covalent bonds or donate these electrons to achieve chemical stability.In the case of the [tex]BH_2[/tex] molecule, boron forms covalent bonds with Hydrogen.These bonds allow the Hydrogens to be positioned on either side of the Boron molecule, forcing a pair of their electrons to focus on the center of that molecule, until it is attracted to the extremities.This allows for a folded geometry around the molecule, allowing Boron to be an exception to the octet rule and achieve stability with 5 electrons in the valence layer.
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Which phrase describes one type of freshwater wetland?
2
acidic areas found in northern climates
reservoirs created by dams at the end of rivers
areas of high elevation that feed into river systems
small streams that flow into larger streams and wetlands
Answer:
The correct answer is D
Explanation:
Wetlands are environments that are either submerged under water or are frequently wet. Marshes, swamps, bogs, and fens are examples of freshwater wetlands. Here small streams flow into larger streams and wetlands. The correct option is D.
Ecosystems in freshwater wetlands are impacted by transient or ongoing flooding. They are essential habitats for fauna (including migratory species), play a significant role in the regulation of water flow and water quality to entire catchments, and offer shelter for fauna during droughts.
In tropical and subtropical areas, mangrove swamps are coastal wetlands. In brackish to saline tidal waters, they are distinguished by halophytic (salt-loving) trees, shrubs, and other plants.
Thus the correct option is D.
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please help me i will give brain list
Answer:
a. pentane = C5H12
b. Heptane = C7H16
c. Hexyne = C6H10
d. Octene = C8H16
e. Nonane = C9H20
Hope it helps.
1-pentene
Molecular Formula C5H10
Condensed Structural FormulaCH2=CH(CH2)2CH3
Melting Point (°C)–138
Boiling Point (°C)30
2- heptane is the straight-chain alkane with the chemical formula H3C(CH2)5CH3 or C7H16, and is one of the main components of gasoline (petrol).