Answer:
$18.30
Explanation:
The change is the amount left over after the selling price has been matched by the buyer.
Let us find the total cost of what of Ms. Kuhn bought;
For the shirt;
Cost = 4 shirts for $15.95 each = 4(15.95) = $63.8
2 new belts for $8.95 each = 2(8.95) = $17.9
Total cost = $63.8 + $17.9 = $81.7
The amount of change left = $100 - $81.7 = $18.3
4. What is the percent by mass of tungsten in the calcium tungstate compound CaWO3, commonly
called scheelite?
Answer: 67.4%
Explanation:
Ca 40.8
W. 183.8
O. 16.00
CaWO3 272.6
W = 183.8/272.6 = 0.674
67.4% percent by mass of tungsten in the calcium tungstate compound CaWO3, commonly called scheelite.
What are calcium tungstate screens?The 200 Speed Blue Emitting Calcium Tungstate Screen is the most commonly used Non-Rare Earth intensifying screen. With a faster speed than Detail or Medium speed screens, the Hi-Plus Intensifying Screen provides an efficient balance between the time patients are exposed during x-rays and image quality and detail.
Who introduced calcium tungstate?It was also used in radium paint in the same fashion as was zinc sulfide, and Thomas Edison invented a fluoroscope with a calcium tungstate-coated screen, making the images six times brighter than those with barium platinocyanide; the latter chemical allowed Röntgen to discover X-rays in early November 1895.
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Which of the following statements about semi-empirical methods are true: It can be used for static molecules but not for reactions in which bonds are forming or breaking. It combines a theoretically sound model of bonding with some experimentally determined parameters. It can determine precisely both the location and the energy of bonding electrons. It is good at predicting structural properties that arise from subtle interactions of orbitals.
Answer:
The true statement about semi-empirical methods is:
It combines a theoretically sound model of bonding with some experimentally determined parameters.
Explanation:
Semi-empirical methods are theoretical assumptions combined with experimental data to improve computational performance. In modern computational chemistry, semi-empirical methods play important roles. The methods offer the advantage of a substantial reduction in computational time. They also increase one's ability to carry out calculations for large molecules. However, with these methods, there is the added loss of the variational principle because one can obtain a total energy that is below the true total energy. Again, semi-empirical methods have limited applicability because the methods apply to molecules with parameterized elements. Semi-empirical methods may supply spurious results, especially since the molecular systems may be different from those used for parameterizations.
The octet rule states that atoms in molecules share electrons in such a way that each atom has a full valence shell. Determine whether each structure has the correct number of electrons and obeys the octet rule. Classify structures that have the correct number of electrons and obey the octet rule as valid, and those that do not as invalid. valid structure invalid structure
Answer:
Their must be a picture with this question so we can answer it
Explanation:
According to octet rule the bonded valence shells are completely filled. All the compounds except the first one, CH₃CH₃O is invalid since H does not obey the rule and invalid.
What is octet rule?Octet rule says that an atoms become stable when it completes its valence shell to 8 electrons or 2 electrons for K-shell. Thus bonded shells have to completely filled to be stable.
Each atom shares its electrons based on its valency. For example carbon have a valency of 4 and it forms for bonds and oxygen and sulfur have two and hydrogen forms only one bonds.
In the first compounds CH₃CH₃O, where one H forms two bonds which is not possible and invalid.
In the second compound CONH, all the atoms satisfies its valency including nitrogen having a valency of three forms three bonds. Similarly in CH₂F₂, one fluorine forms one bond and the structure is valid.
In the case of Br₂ , each bromine shares one electron with the other and complete their octet to eight electrons. In NH₃, SCO and COCl₂ all the atoms satisfies their valency and the structures are valid.
Therefore the only invalid structure is first compound, remaining all are valid.
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Your question is incomplete. But most probably your complete question was as in the uploaded image.
An early version of the Periodic Table had the elements listed in order of increasing relative atomic
mass instead of increasing atomic number. Doing so today would result in the reordering of three
pairs of elements in the first five periods. Identify the three element-pairs.
Answer:
Although he was unaware ofit, Mendeleev had actually placed the elements inorder of increasing “atomic number,” a numberrepresenting the amount of positively charged protons in the atom (also thenumber of negatively charged electronsthat orbit the atom). Mendeleev went even further.
If I dilute 334.75 mL of 1.28 M lithium acetate solution to a volume of 822.18 ml, what
will the concentration of this solution be?
Answer:
C₂ = 0.52 M
Explanation:
Given data:
Initial volume = 334.75 mL
Initial concentration = 1.28 M
Final volume = 822.18 mL
Final concentration = ?
Solution:
C₁V ₁ = C₂V₂
By putting values,
1.28 M×334.75 mL = C₂×822.18 mL
C₂ = 1.28 M×334.75 mL / 822.18 mL
C₂ = 428.48 M.mL / 822.18 mL
C₂ = 0.52 M
Which of the following contains a polyatomic ion?
sodium iodide
carbon monoxide
Iron II oxide
ammonium chloride
Answer:
i think its oxide not too sure
Answer:
Its should be ammonium chloride.
A picture to help you with another question like this
What element has the same electron configuration of 1s2 2s2 2p6 3s2 3p6 ?
Answer:
Ar
Explanation:
1s2|2s2 2p6|3s2 3p6 means 2+2+6+2+6=18 electrones. Also it means the number in the table.
According to the №18 the requested element is Argon.
The element argon with atomic number 18 is found to has the electronic configuration 1s² 2s² 2p⁶ 3s² 3p⁶. Here the element 'Ar' belongs to the 18th group of the periodic table.
What is electronic configuration?The electronic configuration is defined as a method which represents the arrangement of electrons in the atomic orbitals. Each of the elements have a unique electronic configuration.
The physical, chemical and magnetic properties of the elements can be predicted by knowing their electronic configuration. Sometimes the term electron structure can also be used instead of electronic configuration.
The species K⁺ ion has the same electronic configuration of 'Ar'. The atomic number of 'K' is 19 and K⁺ is formed by the lose of one electron from 'K'. Here K⁺ has 18 electrons and its electronic configuration is:
1s² 2s² 2p⁶ 3s² 3p⁶.
Thus the element argon has the electronic configuration 1s² 2s² 2p⁶ 3s² 3p⁶.
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Why is glass NOT a crystal?
A its is a solid
B it is transparent
C it is not a crystalline
D it fractures
Answer:
I think it's B- it is transparent
Answer:A
Explanation:Glass can not be classified as a crystal when it is in its amorphous phase.
What best describes how the processes of scientific
investigation and technological design are involved in
this situation?
O The clothing company conducted a scientific
investigation to communicate results to researchers,
who then used the knowledge in a technological
design.
O The clothing company conducted a scientific
investigation to produce a product that researchers
could then test while designing new technology.
O The clothing company used technological design to
create a product that helped aid researchers
conducting a scientific investigation.
O The clothing company designed a new technology
that provided information researchers needed in order
to continue with their scientific investigation.
Answer:
O The clothing company conducted a scientific investigation to communicate results to researchers, who then used the knowledge in a technological
design.
Explanation:
The products of scientific investigation are converted into technology for use engineers.
Engineering is the application of science to solve life problems. Science in itself is an inquiry into nature.
Science uses a series of methodical approaches to conduct investigations and researches. The product of the research is taken up by an engineer. The engineer deploys this into the right and applicable technology available. In the clothing company, the product of the investigation are relayed to the engineers who uses technological innovations to design a new tool for use.Write a balanced chemical equation for the reaction of aqueous solutions of lead(II) nitrate and potassium iodide
to produce solid lead (II) iodi de and aqueous potassium nitrate.
Help pleaseee
Answer: Pb(NO3)2(aq) + 2KI(aq) —> PbI2(s) + 2KNO3(aq)
Explanation:
A desert that contains plants and animals that have been there a long time is
an example of
When I freeze a water bottle and it breaks open is it because the ice has more matter than the water inside?
The atomic number of an atom is always equal to the total number of
A. neutrons in the nucleus
B. protons in the nucleus
C. neutrons plus protons in the atom
D. protons plus electrons in the atom
Answer:
yep C is correct!!
Explanation:
A mixture in which one substance is evenly mixed with another substance is called a..
A) Solvent
B)Solute
C)Solution
D) Heterogeneous
Answer:
C solution
Explanation:
i hope that i got it right im not very good with questions
What is the iupac name of the following compound?
2,2-dimethyl-4-ethylheptane
Answer:
The IUPAC name of the compound has already been given which is 2,2-dimethyl-4-ethylheptane.
Explanation:
The IUPAC (International Union of Pure and Applied Chemistry) is an authority in chemistry that provides a guideline and standardized methods in the naming of compounds formed from the periodic table.
In order the give an IUPAC name to a compound, certain steps needs to be followed, these includes:
--> Identify the functional group in the compound as this will form the suffix. For example if the functional group is an alkane the suffix will be -ane.
--> Identify the longest carbon chain (it may not be a straight chain) that contains the functional group. This forms the prefix. Example: if the longest carbon chain is 7 carbon atoms then the prefix will be hept-
--> All the carbons of the longest chain should be numbered
--> Identify branched groups on the chain and name them according to the number of carbon atoms. They usually end with -yl.
--> Finally, combine the elements of the name is a single word.
The structural formula of the IUPAC compound can be found in the attached file for a better understanding. The branched groups are circled.
Match each term to its description. (3 points)
Excess reactant
Theoretical Yield
Limiting Reactant
1. Reactant that can produce more of
the product
2. Reactant that can produce a lesser
amount of the product
3. Amount of product predicted to be
produced by the given reactants
Answer:
1. B 2. C 3. A
Explanation:
I just took it
Limiting reactant is the reactant the produces the least amount of the product.
In a chemical reaction, the reactant that is in least supply is the limiting reactant while the reactant that is more than required is the excess reactant.
To match each term with its description, we have;
Excess reactant - Reactant that can produce more ofthe product
Limiting Reactant - Reactant that can produce a lesseramount of the product
Theoretical Yield - Amount of product predicted to beproduced by the given reactants
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Some fireplace logs (commercially made) burn with a red and/or green flame. Using the information in this experiment, what elements could be responsible for these colored flames?
Answer:
Because each element has an exactly defined line emission spectrum, scientists are able to identify them by the color of flame they produce. For example, copper produces a blue flame, lithium, and strontium a red flame, calcium an orange flame, sodium a yellow flame, and barium a green flame. 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 colors. Each metal gives a characteristic flame emission spectrum
1 Define Soft water and Hard water.
Answer:
software is a collection of codes installed onto your computer hard drive and hardware is any physical device that we used in or with your machine.
hope it helps.
Answer: soft water is water with a low concentration of ions and hard water is one with a high concentration of water e.g rainwater
Explanation:
what is the formula for H-H
Answer:
H-H equation is written as follows:
pH=pK + log
{HCO3-}(base)
{H2CO3}(acid)
Given:
BO3 + 3Mg → 3MgO + B
1. How many moles of Mg are required if 2 moles of B are produced?
Answer:
6moles of Mg
Explanation:
The reaction expression is given as:
BO₃ + 3Mg → 3MgO + B
Given:
Number of moles of B produced = 2 moles
Unknown:
Number of moles of Mg required = ?
Solution:
From the balanced reaction expression:
1 mole of B is produced from 3 moles of Mg
2 moles of B will be produced from 2 x 3 = 6moles of Mg
What is the function of the chloroplast? A. Breaks down sugar to make energy B. To hold the cell together C. To make animals green D. Uses sunlight to create glucose (sugar)
Answer:
D. Uses sunlight to create glucose (sugar)
Explanation:
The function of the chloroplast is that it uses sunlight to create glucose.
The chloroplast allows for light to be trapped which is used for the synthesis of glucose from carbon dioxide and water.
The chloroplast is a rich in a pigment called the chlorophyll. This chlorophyll is a green pigment which allows for the trapping of solar energy
This solar energy is used to carryout the photosynthetic reaction.
WORTH 40 POINTS HELLPPPP
What class of element is Astatine (At)?
Answer:
halogen.
nonmetal.
Explanation:
definition of solubility
(science)
Answer:
th relative ability of a solute to devolve into a solvent
The normal boiling point of a certain liquid X is 141.70 °C, but when 68.1 g of barium hydroxide (Ba(OH)) are dissolved in 750. g of X the solution boils at 142.5C instead. Use this information to calculate the molal boiling point elevation constant
Answer:
Explanation:
Normal boiling point = 141.7°C
Elevated boiling point = 142.5°C
Elevation of boiling point Δt = 0.8°C
Formula for elevation of boiling point is as follows .
Δt = 1000 x Kb x w / (MW )
where w is weight of solute , M is molecular weight of solute , W is weight of solvent in grams, Kb is molal boiling point elevation constant .
Mol weight of barium hydroxide = 171 .
.8 = 1000 x Kb x 68.1 / (171 x 750 )
Kb = 1.5°C / m
A flask contains 0.160 mol of liquid bromine, what are the number of bromine molecules present
Answer:
9.64 x 10^22
Explanation:
To go from moles to molecules, you multiply by Avogadro's number, 6.022 x 10^23, so you get 9.64 x 10^22.
How many moles of phosphoric acid would be needed to produce 15 grams of water?
Moles of phosphoric acid would be needed : 0.833
Further explanationGiven
15 grams of water
Required
moles of phosphoric acid
Solution
Reaction(decomposition) :
H3PO4 -> H2O + HPO3
mol water (H2O :
= mass : MW
= 15 g : 18 g/mol
= 0.833
From the equation, mol ratio H3PO4 = mol H2O = 1 : 1, so mol H3PO4 = 0.833
A chemist has a block of copper metal (density is 8.96). They drop the metal into a graduated cylinder containing water, and find the volume change is 2.90 mL. What is the mass of the block , in grams?
Answer:
26g
Explanation:
Given parameters:
Density = 8.96g/cm³
Volume of metal = 2.9mL
Since 1mL = 1cm³;
Volume = 2.9cm³
Unknown:
Mass of the blocks in grams = ?
Solution:
Density is the mass per unit volume of a substance;
Mass = density x volume = 8.96 x 2.9 = 26g
A brown dye has a percent composition of 62.41% C, 5.24% H, and 32.36% N by mass with a molar mass of 346.40 g/mol. Determine the molecular formula of the dye
The molecular formula : C₁₈H₁₈N₈
Further explanationGiven
62.41% C, 5.24% H, and 32.36% N
Required
The molecular formula
Solution
mol ratio
C : 62.41/12.0096 = 5.1967
H : 5.24/1.00784 = 5.1992
N : 32.36/14.0067 = 2.310
Divide by 2.310(smallest)
C : 5.1967/2.31=2.25
H : 5.1992/2.31 = 2.25
N : 2.31/2.31 = 1
Multiplied by 4
C : H : N = 9 : 9 : 4
The empirical formula : C₉H₉N₄
(C₉H₉N₄)n=346.40 g/mol
(12.0096 x 9 + 1.00784 x 9 + 14.0067 x 4)n=346.4
(108.0864+9.07056+56.0268)n=346.4
(173.184)n=346.4
n=2
The molecular formula : C₁₈H₁₈N₈
According to bond energy tables, the triple bond of N2 is 946 kJ/mol while the bond of I2 is 151 kJ/mol. Based on simple chemical ideas about what molecular properties lead to activation energies, it is reasonable to expect that the reaction of H with N2 will have a higher activation energy than the reaction of H with I2.
1. Yes, I2 is heavier than N2.
2. No, bond energies do not matter much; lone pairs are crucial.
3. Yes, in both cases the reactant bond must be stretched by collisions and more energy is required for the stronger bond.
4. Yes, in both cases the reactant bond must be broken before the H can bond.
5. No, activation energies have nothing to do with bond energies.
Answer:
Yes, in both cases the reactant bond must be broken before the H can bond.
Explanation:
Let us remind ourselves of the basics of the collision theory. According to this theory, chemical reaction occurs because of the collision of particles of substances in a chemical reaction system.
This means that the bond between reactants must first be broken and new bonds formed in products. Activation energy is the minimum energy required for a reaction to occur. This energy goes into the rearrangement of reactant bonds to enable them to recombine and form products.
Since the N2 bond energy is far higher than the I2 bond energy, a greater degree of energy is needed overcome the energy barrier in the reaction of H2 with N2 compared to the reaction of H2 and I2 . Therefore, the activation energy for the reaction of H2 and N2 is much higher than the activation energy for the reaction of H2 with I2.
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