Answer:
b
Explanation:
An unknown element X has the following isotopes: ²⁵X (80.5% abundant) and ²⁷X (19.5% abundant). What is the Average atomic mass in amu of X?
Answer:
the average atomic mass in amu of X is 25.39 amu
Explanation:
The computation of the average atomic mass in the amu of X is shown below:
Average mass is
= Product sum + atomic mass of each and every isotope
Now the average mass
= (80.5 ÷ 100 × 25 amu) + (19.5 ÷ 100 × 27 amu)
= 20.125 + 5.265
= 25.39 amu
Hence, the average atomic mass in amu of X is 25.39 amu
The average atomic mass of X is 25.39 amu.
Atomic massIt is the quantity of matter present within an atom of an element.
Based on the given information,
• The unknown element X has the isotopes, 25X (80.5% abundant) and 27X (19.5% abundant).
Now the atomic mass of X can be calculated by using the formula,
[tex]=\frac{(M1*A1)+(M2*A2)}{A1+A2}[/tex]
Here, M1 and M2 are the atomic masses, and A1 and A2 are their abundances.
Now putting the values we get,
[tex]= \frac{(25*80.5)+(27*19.5)}{80.5+19.5} \\\\= \frac{2012.5+526.5}{100} \\= \frac{2539}{100} \\= 25.39 amu[/tex]
Thus, the average atomic mass of X is 25.39 amu.
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(The radioisotope 224Ra decays by alpha emission via two paths to the ground state of its daughter 94% probability of alpha decay directly to the daughter ground state;(20 pts, 5 pts each)5.5% probability of alpha decay to an excited state before emitting a 0.241 MeV photon in an isomeric transition to reach the ground state of the daughter.a.Write the reaction equation for the alpha decay of 224Ra. b.Calculate the Q-value (in MeV) of this reaction. c.What are the energies (in MeV) of the two associated alpha particles? d.Sketch the decay scheme for the decay of 224Ra with the associated probabilities, energies, and emissions for the a
Answer:
a) ²²⁴Ra₈₈ ---> α + ²²⁰Rn₈₆ + Q
b) the Q-value of this reaction is 5.789 MeV
c) the energies (in MeV) of the two associated alpha particles are; 5.69 MeV and 5.449 Mev
Explanation:
a)
The decay equation for the alpha decay is expressed as;
²²⁴Ra₈₈ ---> α + ²²⁰Rn₈₆ + Q
b)
Calculate the Q-value (in MeV) of this reaction.
Q = Mparent - Mdaughter -Mg
Q = MRa - MRn -Mg
= 224.020202 - 220.011384 - 4.00260305
= 0.00621495 amu
= 5.789 MeV
therefore the Q-value of this reaction is 5.789 MeV
c)
Energy of alpha particle is expressed as;
E∝ = MQ / ( m + M)
now this is the maximum energy available for the daughter, ²²⁰Rn going to the ground state;
The energy of the alpha particle gives;
E∝ = 220(5.789) / ( 4 + 220) = 5.69 MeV
as given in the question,The other less frequent alpha occurring 5.5% of the time leaves the daughter nucleus in an excited state of 0.241 MeV above the ground state.
Therefore the energy of this alpha is
E∝ = 5.69 - 0.241 = 5.449 Mev
Therefore the energies (in MeV) of the two associated alpha particles are; 5.69 MeV and 5.449 Mev
d)
Sketch of the nuclear decay scheme have been uploaded along side this answer.
(a)[tex]^{224}Ra_{_{88}}=^4\alpha_{_2}+^{220}Rn_{_{86}}+Q[/tex]
(b) the Q-value of the reaction is 5.789 MeV
(c) The alpha particles have energies of 5.69 MeV and 5.449 MeV
Alpha decay:(a) The alpha decay of the radioisotope 224Ra is given by:
[tex]^{224}Ra_{_{88}}=^4\alpha_{_2}+^{220}Rn_{_{86}}+Q[/tex]
(b) The Q-value of a reaction is given by:
Q = {mas of reactants - mass of products}c²
[tex]Q = [M_{224Ra} - M_{\alpha} - M_{220Rn}]c^2[/tex]
Q = (224.020202 - 220.011384 - 4.00260305) amu.c²
Q = 0.00621495 × 931.5 MeV ( since 1 amu.c² = 931.5 MeV)
Q = 5.789 MeV
(c) The energy of the alpha particle is expressed as;
E(α) = MQ / ( m + M)
it is the maximum energy available for the daughter nucleus, ²²⁰Rn going to the ground state.
If the daughter nucleus is at rest then all the energy is carried by the alpha particle.
The energy of the alpha particle is:
E(α) = 220(5.789) / ( 4 + 220) = 5.69 MeV
Now, for the alpha particle occurring 5.5% of the time and leaving the daughter nucleus in an excited state of 0.241 MeV :
The energy of this alpha particle is
E(α) = 5.69 - 0.241 = 5.449 Mev
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Convert 533 cm/s to units of meters per minute. Show the unit analysis by dragging the conversion factors into the unit‑factor slots
Answer:
319.8 m/min
Explanation:
533 cm/s
We can convert 533 cm/s to m/min by doing the following:
First, we shall convert 533 cm/s to m/s. This can be obtained as illustrated below:
Recall:
100 cm/s = 1 m/s
Therefore,
533 cm/s = 533 cm/s /100 cm/s × 1 m/s
533 cm/s = 5.33 m/s
Finally, we shall convert 5.33 m/s to m/min. This can be obtained as follow:
1 m/s = 60 m/min
Therefore,
5.33 m/s = 5.33 m/s / 1 m/s × 60 m/min
5.33 m/s = 319.8 m/min
Therefore, 533 cm/s is equivalent to 319.8 m/min
What is the density of a copper blocks if it has a mass of 43.5 grams and a volume of 4.85 cm^3?
What causes the flame colors when salts are exposed to the flame? (hint: electrons jump
between different energy levels)
Answer:
When you heat an atom, some of its electrons are "excited* to higher energy levels. When an electron drops from one level to a lower energy level, it emits a quantum of energy. ... The different mix of energy differences for each atom produces different colours. Each metal gives a characteristic flame emission spectrum.
Explanation:
hrough the complete electrolysis of a sample of pure water, a student collects 14.0 grams of hydrogen gas and 112.0 grams of oxygen gas. What mass of water (in grams), if it reacted completely, was initially present? (The electrolysis of water is the use of an electric current to decompose it into its component elements.)
Answer:
126g of H₂O
Explanation:
Electrolysis of water is:
2H₂O(l) → 2H₂(g) + O₂(g).
To know mass of water that reacted, we need to find moles of hydrogen and oxygen and, by using electrolysis chemical equation, we can determine moles of water and its mass, thus:
Moles hydrogen (Molar mass: 2.01g/mol):
14.0g H₂ * (1mol / 2.01g) = 6.97 moles hydrogen
Moles Oxygen (Molar mass: 32g/mol):
112.0g O₂ * (1 mol / 32g) = 3.5 moles oxygen
As 2 moles of hydrogen and 1 mole of oxygen are produced from 2 moles of water, and 7 moles of hydrogen and 3.5 moles of oxygen were collected, moles of water that reacted were 7 moles H₂O.
As molar mass of water is 18g/mol, mass of 7 moles of H₂O is:
7 mol H₂O * (18g / mol) =
126g of H₂OWhat is chemistry?
A. The scientific study of matter
B. The study of living things
C. The study of how matter and energy interact
D. The study of changing ideas
Answer:
the scientific study of matter i believe
Explanation:
because the definition says the branch of science that deals with the identification of the substances of which matter is composed
Katrina is investigating the properties of volume for the different states of matter. First, she places a cube in a bowl of water and observes what happens. Next, she takes the cube out of the water and pours the water into a glass. Which statement describes the observations Katrina made? A. When the cube was placed in the water, the volume and shape stayed the same. When the liquid was poured from the bowl, the shape changed. B. When the cube was placed in the water, the volume of the water changed. When the liquid was poured from the bowl, the shape changed. C. The volume of the cube and the water changed when the cube was placed into the water. The volume of the liquid changed when it was poured out of the bowl. D. The shape and volume of the cube and the liquid changed when the cube was placed in the bowl. The liquid stayed the same when it was poured from the bowl.
Answer:
When the cube was placed in the water, the volume of the water changed. When the liquid was poured from the bowl, the shape changed.
Explanation:
When a cube is placed inside water, the volume of the water will change due to the introduction of the cube as the cube will displace some water. Remember that the shape of a liquid is the shape of its container so the shape of the water remains the same.
When the water is poured into a glass, its shape changes as it now assumes the shape of the glass as explained above.
Answer: When the cube was placed in the water, the shape of the cube stays the same. When the liquid was poured from the bowl into the glass, the shape changed
Explanation:
Science is a way of discovering what's in the natural world and how those things
A)
work today
B)
how they worked in the past
C)
how they are likely to work in the future
D)
work today, how they worked in the past, and how they are likely to work
in the future
Answer:
D
Explanation:
science shows patterns and anomalies in how the world works
Which type of basin forms at divergent boundaries
Answer:
A: rift
Explanation:
Divergent boundaries within continents initially produce rifts, which produce rift valleys.
Answer:
rift just did the quiz
Rank the following compounds from least acidic(rank 1) to most.A. AcetaldehydeB. Methyl acetate.C. N,N-dimethylacetamide1. least acidic2. most acid
Answer:
N,N-dimethylacetamide < Methyl acetate < Acetaldehyde
Acetaldehyde - least acidic
Methyl acetate - acidic
N,N-dimethylacetamide - most acidic
Explanation:
The order of acidity of the organic compound under study is primarily influenced by their resonance effect. The resonance effect explains how polar a particular molecule is from the interaction between pi -bonds or a lone electron pair and a pi-bond in a molecule.
In acetaldehyde popularly known as ethanal, the CH₃CHO functional group -CHO is attached to an adjacent end of the compound, which has a lesser resonance effect than methyl acetate.
Methyl acetate, also known as methyl ethanoate, is an ester family with the formula CH₃COOCH₃ is also lesser in its acidity compared to N,N-dimethylacetamide.
Therefore, the order of acidity from the least acidic to the most is:
N,N-dimethylacetamide < Methyl acetate < Acetaldehyde
Acetaldehyde - least acidic
Methyl acetate - acidic
N,N-dimethylacetamide - most acidic
A 38.6 kg marble slab is shown above. What is it’s density? Give you’re answer to the nearest tenth
Answer:
Density, [tex]d=24.68\ g/cm^3[/tex]
Explanation:
Given that,
Mass of marble slab is 38.6 kg or 38600 g
The dimensions of the slab is 23 cm × 17 cm ×4 cm
We know that the density of an object is given in terms of its mass volume as follows :
[tex]d=\dfrac{\text{mass}}{\text{volume}}\\\\d=\dfrac{38600\ g}{1564\ cm^3}\\\\d=24.68\ g/cm^3[/tex]
So, the density of the marble slab is [tex]24.68\ g/cm^3[/tex]
6. The SI unit of weight is a newton (N). If a boulder weighs 240 N
on Earth, what is its weight on the moon?
a 40N
b 60 N
C 240 N
d 120 N
Answer:
A. 40N
Explanation:
What is the name of the binary molecule H2O2? This compound is also known as hydrogen peroxide and is a properly disinfectant or cuts and scrapes.
Answer:
hydrogen dioxide
Explanation:
Hydrogen dioxide is the name of the binary molecule H2O2 ,therefore option (b) is correct from the image below.
What do you mean by hydrogen dioxide ?A thick, colorless liquid, H2O2, resembling water, but having a bitter, sour taste, produced by the action of acids on barium peroxide.
It decomposes into water and oxygen, and is manufactured in large quantities for an oxidizing and bleaching agent. Called also oxygenated water.
A colorless, unstable compound of hydrogen and oxygen (H 2 O 2). It is used as an antiseptic and bleaching agent.
Hydrogen dioxide is the name of the binary molecule H2O2 ,hence option (b) is correct from the image below.
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A chemist measures the energy change ?H during the following reaction: 2HgO (s) ?2Hg (l) +O2 (g) =?H182.kJ Use the information to answer the following questions. This reaction is...
endothermic.
exothermic.
Suppose 72.8g of HgO react. Will any heat be released or absorbed?
Yes, absorbed.
Yes, released.
No.
If you said heat will be released or absorbed in the second part of this question, calculate how much heat will be released or absorbed. kJ Round your answer to 3 significant digits. ×10
Answer:
The reaction is endothermic.
Yes, absorbed
3.06x10¹kJ are absorbed
Explanation:
In the reaction:
2HgO(s) → 2Hg(l) + O₂(g) ΔH = 182kJ
As ΔH >0,
The reaction is endothermic
As the reaction is endothermic, when the reaction occurs,
the heat is absorbed.
Now, based on the equation, when 2 moles of HgO (Molar mass: 216.59g/mol), 182kJ are absorbed.
72.8g are:
72.8g * (1mol / 216.59g) = 0.3361 moles HgO.
that absorb:
0.3361 moles HgO * (182kJ / 2 moles) =
3.06x10¹kJ are absorbed3root 7
Prove that
Irrational
C=82.76% H=17.24% Molecular formula ???
Answer:
ok
Explanation:
Element %composition Mol. mass No. of C atoms Simplest Rounding
ratio off
C 82.76 12 6.89 1× 2 2
H 17.24 1 17.24 2.5× 2 5
Number of carbon atoms present =
12
82.76
=6.89
Number of hydrogen atoms present =
1
17.24
=17.24
simplest ratio =
6.89
6.89
=1
simplest ratio =
6.89
17.24
=2.5
∴ Empirical fromula is C
2
H
5
Empirical formula mass= 2×12+5 = 29
∴ V.D. = 29
Mol. mass = 2 × V.D.
=58
n=
Empiricalformulamass
Molecularmass
=
29
58
=2
∴ Molecular formula = C
4
H
10
pls mark me as braillant
Identify structure(s) for all constitutional isomers with the molecular formula C4H8 that have one double bond. Select all that apply.
Answer:
a) But-1-ene
b) E-But-2-ene
c) Z-But-2-ene
d) 2-Methylpropene
Explanation:
In this case, if we want to draw the isomers, we have to check the formula [tex]C_4_H8[/tex] in this formula we can start with a linear structure with 4 carbons. We also know that we have a double bond, so we can put this double bond between carbons 1 and 2 and we will obtain But-1-ene.
For the next isomer, we can move the double bond to carbons 2 and 3. When we do this can have two structures. When the methyl groups are placed on the same side we will obtain Z-But-2-ene. When the methyls groups are placed on opposite sides we will obtain E-But-2-ene.
Finally, we can use a linear structure of three carbons with a methyl group in the middle with a double bond, and we will obtain 2-Methylpropene.
See figure 1 to further explanations.
I hope it helps!
The van der Waals equation for real gases recognizes that:
A. the molecular attractions between particles of a gas decrease the pressure exerted by the gas
B. the non-zero volumes of gas particles effectively decrease the amount of "empty space" between them
C. gas particles have non-zero volumes and interact with one another
D. molar volumes of gases of different types are different
E. All of the above statements are correct
Answer:
E. All of the above statements are correct
Explanation:
The gas equation given below and which we are familiar with relates to ideal gases and not to real gases .
P V = R T
In this equation , it has been assumed that gas molecules have no mutual attraction . They do not occupy any space ie they are very small in volume . But in reality , gas molecules do have mutual attraction and also they occupy some space. . Considering these facts , a new formula was given to replace the gas equation which is written below .
(P - a / V² ) ( V - b ) = R T , a and b are constant and depend upon nature of gas involved .
This is called van der Waals equation . This is for one mole .
Here we see P of previous gas equation is replaced by P - a / V² .
That means pressure of real gas is less than the ideal gas . It is due to mutual attraction between any two gas molecules. V of previous gas equation is replaced by V - b . That means volume of empty space has been reduced . It is due to the fact that real gas molecules occupy some space . Here b is dependent on the nature of the gas.
So all the statements are correct .
The van der Waals equation for real gases recognizes that gas particles have non-zero volumes and interact with one another.
The ideal gas equation is used to describe the relation among the volume, pressure and temperature of an ideal gas. Recall that the ideal gas equation holds that there is no intermolecular interaction between gas molecules and that gas molecules occupy zero volume relative to the volume of the container.
The van der Waals equation for real gases recognizes that gas particles have non-zero volumes and interact with one another.
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which of the following is NOT a chemical property?
Conductivity
Malleability
Reactivity
Freezing
Answer:
Malleability
Explanation:
Answer:
Malleability is not chemical property
One way to represent this equilibrium is: 2 CO2(g) + 4 H2O(g)2 CH3OH(l) + 3 O2(g) We could also write this reaction three other ways, listed below. The equilibrium constants for all of the reactions are related. Write the equilibrium constant for each new reaction in terms of K, the equilibrium constant for the reaction above. 1) CH3OH(l) + 3/2 O2(g) CO2(g) + 2 H2O(g) K1 = 2) 2 CH3OH(l) + 3 O2(g) 2 CO2(g) + 4 H2O(g) K2 = 3) CO2(g) + 2 H2O(g) CH3OH(l) + 3/2 O2(g)
Answer:
1) 1/√K
2) 1/K
3) √K
Explanation:
As general rules of operation of equilibrium constants:
For the reaction:
A + B ⇄ C + D; Equilibrium constant = K
C + D ⇄ A + B; K' = 1/K
2A + 2B ⇄ 2C + 2D; K'' = K²
Thus, as equilibrium constant of:
2CO2 + 4H2O ⇄ 2CH3OH + 3O2
Is K:
1) CH3OH + 3/2 O2 ⇄ CO2 + 2H2O
K' = 1 / K^(1/2) = 1/√K
2) 2CH3OH + 3O2 ⇄ 2CO2 + 4H2O
K' = 1/K
3) CO2 + 2H2O ⇄ CH3OH + 3/2 O2
K' = K^(1/2) = √K
Explain the significance of:_______. a) a very large value of K, b) a very small value of K, and c) a K value of about 1.0.
Answer:
See explanation
Explanation:
a) A large value of K shows that the reaction is product favoured. It implies that more reactants are converted to products and the equilibrium concentration of products in the system is far higher than that of the reactants. The reaction will proceed towards the right hand side.
b)A small value of K implies that the reaction is reactant favoured. There are more reactants than products present at equilibrium and the reaction will proceed towards the lefthand side.
c) K=1 implies the presence of a significant concentration of reactants and products in the system at equilibrium.
Alexander is measuring the width of objects. The smallest measurement his ruler displays is centimeters. Rather than
rounding to one significant figure beyond what he can measure with certainty, he rounds his data to the nearest centimeter to
make his math easier. Enter the amount of uncertainty that is created by this rounding error.
Answer:
There can be error in millimetres.
Explanation:
The rounding off can create errors in exact measurement. There can be errors in the measured value and actual measurement of the object. Alexander has rounded his calculation to nearest centimetre then it is possible he can make errors in millimetre calculations. The measured width of the object will not be the actual measurement and it might differ slightly.
How is energy transformed from one form to another? Give three examples of objects that have potential energy and kinetic energy? What does the law of convosation of energy state? .
Answer:
An energy transformation is the change of energy from one form to another. Energy transformations occur everywhere every second of the day. There are many different forms of energy such as electrical, thermal, nuclear, mechanical, electromagnetic, sound, and chemical.
Explanation:
The measured quantity 0.00410 g written in scientific notation is _______. Using prefixes, the number can be written as ________.
Answer:
4.10x10⁻³g.
4.10 mg.
Explanation:
Hello,
In this case, considering the given number, we can see it has two digits after the first nonzero digit that is four (4) which is also at the third decimal place, it means that the scientific notation has a negative power as it is at the left of the given zeros, therefore it is:
4.10x10⁻³g.
Moreover, since the proper prefix for the factor x10⁻³ is milli, the number with prefix is:
4.10 mg.
Best regards.
Which of the following is a mixture? honey water gold steel
Answer:
steel because water gold and honey is not a mixture of something
Answer:
Steel
Explanation:
What is the density of an object that has a mass of 6.5 g and when placed in water displaces the volume from 4.5mL to 11.8mL? round to the nearest tenth
Answer:
[tex]\rho =0.9g/mL[/tex]
Explanation:
Hello,
In this case, due to the volume displacement caused the by the object's submersion, it's volume is:
[tex]V=11.8mL-4.5mL=7.3 mL[/tex]
In such a way, considering the mathematical definition of density, it turns out:
[tex]\rho =\frac{m}{V}=\frac{6.5g}{7.3mL}\\ \\\rho =0.89g/mL[/tex]
Rounding to the nearest tenth we finally obtain:
[tex]\rho =0.9g/mL[/tex]
Regards.
Which of the following is the conjugate acid of water?
Answer:
Hydronium ion
The conjugate acid of water is the hydronium ion ; [tex]H_3O^+,[/tex]
Explanation:
It is an ion formed by the association of a hydrogen ion with a water molecule.
Look at the image below:
Which of the following statements is true?
Group of answer choices
The figure is a molecule and a compound.
The figure is a compound, but not a molecule.
The figure is an atom and an element.
The figure is a molecule and an element.
Answer:
The figure is a molecule and a compound
Explanation:
Because it have 2 cluster molecules
Data Tables Practices
Table 1 Information: Allison wanted to find out if the color of soda affected whether her friends would
choose a particular one. She collected the following data:
Orange Soda - 5 friends
Yellow Soda - 7 friends
Green Soda - 2 friends
Clear Soda - 1 friend
Brown Soda - 15 friends
Table 1 Title:
Independent Variable:
Dependent Variable:
Make a data table in this space, include labels for variables and the title:
Page
2
+
/ 5
Answer:
Title: Effect of soda color on the choice of Allison's friends.
Independent variable: Color of Soda
Dependent variable: Friends' choice/Number of friends that chose a particular soda
Please find the data table attached as an image.
Explanation:
A data table is used to organize the data recorded after an experiment. The data table shows the title of the experiment, which is written directly above the table. It also shows the independent variable (on the first column) and the dependent variable (on other columns to the right).
- In this experiment, the title of the data table can be written as EFFECT OF COLOR OF SODA ON THE CHOICE OF ALLISON'S FRIENDS.
- The independent variable is the manipulated or changed variable, which is the COLOR OF SODA in this case.
- The dependent variable is the variable that is measured in an experiment, which is the NUMBER OF FRIENDS THAT CHOSE EACH SODA in this case.