Answer:
b
Explanation:
Answer:
B
Explanation:
What are some of the reasons why the United States did not adopt the metric system of measure?
at the time most of its trade was with France who did not use the metric system
the House of Representatives defeated the bill calling for conversion to metrics in 1974
the US was waiting for all other industrialized countries to adopt it before proceeding
at the time most of its trade was with England and Canada who did not use the metric system
Answer: in 1975, the United States passed the Metric Conversion Act. The legislation was meant to slowly transition its units of measurement from feet and pounds to meters and kilograms, bringing the US up to speed with the rest of the world. There was only one issue: the law was completely voluntary. Of course, that meant it pretty much never took off
Explanation:
they passed the metric act
what is the atomic structure of an element that has atomic number of 11 and neutron number of 12.
Answer:
See explanation
Explanation:
The atomic number refers to the number of protons in the nucleus, it also tells us the number of electrons in the neutral atom since the atom is electrically neutral because the number of protons and electrons are equal.
If an atom has the atomic number 11, then the electrons in the atom are arranged in the shells in the order; 2, 8, 1.
Two electrons are found in the innermost shell, eight electrons are found in the next shell and one electron is found on the outermost shell.
The nucleus of the atom is composed of a total of 23 nucleons; 11 protons and 12 neutrons.
Suppose a piece of silver jewelry contains 7.49x10^22 atoms of silver (Ag). how many moles of silver are in the jewelry?
Answer:
0.124 mol Ag
General Formulas and Concepts:
Atomic Structure
MolesStoichiometry
Using Dimensional AnalysisExplanation:
Step 1: Define
[Given] 7.49 × 10²² atoms Ag
[Solve] mol Ag
Step 2: Identify Conversions
Avogadro's Number - 6.022 × 10²³ atoms, molecules, formula units, etc.
Step 3: Convert
[DA] Set up: [tex]\displaystyle 7.49 \cdot 10^{22} \ atoms \ Ag(\frac{1 \ mol \ Ag}{6.022 \cdot 10^{23} \ atoms \ Ag})[/tex][DA] Divide [Cancel out units]: [tex]\displaystyle 0.124377 \ mol \ Ag[/tex]Step 4: Check
Follow sig fig rules and round. We are given 3 sig figs.
0.124377 mol Ag ≈ 0.124 mol Ag
Topic: AP Chemistry
What is the initial pressure of a gas if it’s occupied a volume of 0.375 L but now occupies a volume of 1.25 L at a pressure of 95.5 K PA
Answer:
318 kPa
Explanation:
Step 1: Given data
Initial pressure (P₁): ?Initial volume (V₁): 0.375 LFinal pressure (P₂): 95.5 kPaFinal volume (V₂): 1.25 LStep 2: Calculate the initial pressure of the gas
Assuming constant temperature and ideal behavior, we can calculate the initial pressure of the gas using Boyle's law.
P₁ × V₁ = P₂ × V₂
P₁ = P₂ × V₂ / V₁
P₁ = 95.5 kPa × 1.25 L / 0.375 L = 318 kPa
Consider these two cases.
Case 1: An electron jumps from energy level 1 to energy level 2 in an atom.
Case 2: An electron jumps from energy level 1 to energy level 3 in an atom.
For case 1, what happens when an electron jumps from energy level 1 to energy level 3 in an atom?
A. A photon is absorbed by the atom.
B. A photon is emitted by the atom.
C. A proton is absorbed by the atom.
D. A proton is emitted by the atom.
Assuming that both cases describe Hydrogen-like atoms with one electron, for which case is more energy emitted or absorbed?
A. The energy is the same for both cases.
B. More energy is emitted or absorbed for case 2
C. It is impossible to tell.
D. More energy is emitted or absorbed for case 1
Answer:
A photon is absorbed by the atom.
More energy is emitted or absorbed for case 2
Explanation:
According to the Bohr model of the atom, electrons occur in energy levels. The energy of each level is fixed. However, electrons can absorb photons and move from a lower to higher energy level or emit photons and move from a higher to a lower energy level.
In each case, the energy absorbed or emitted is equal to the difference in energy between the two energy levels.
Since energy level 3 is much higher than energy level 2, the electron absorbs more energy in moving from energy level 1 to energy level 3 than it absorbs when moving from energy level 1 to energy level 2.
When the following oxidation-reduction reaction in acidic solution is balanced, what is the
lowest whole-number coefficient for Rb+ (aq)?
Rb(s) + Sr2+ (aq) → Rb+(aq) + Sr(s)
Answer:
2Rb(s) + Sr^+(aq) → 2Rb^+ (aq) + Sr(s)
Explanation:
In a redox reaction, we must ensure that the number of electrons gained equals the number of electrons lost in the reduction and oxidation half reaction equations respectively.
Having that in mind;
Oxidation half reaction;
2Rb(s) ---->2Rb^+(aq) + 2e
Reduction half equation;
Sr^2+(aq) + 2e---> Sr(s)
Hence, the overall redox reaction equation is;
2Rb(s) + Sr^+(aq) → 2Rb^+ (aq) + Sr(s)
The "nitrogen rule" of mass spectrometry requires a compound containing an odd number of nitrogens to have an odd-mass molecular ion and a compound containing an even number of nitrogens to have an even-mass molecular ion. What is the molecular formula of the CHN-containing compound pyrazine, M+ = 80? (The order of atoms should be carbon, then hydrogen, then others in alphabetical order.)
Answer:
C₄H₄N₂
Explanation:
Given that:
M+ = 80.
It implies that the number of nitrogen present in the molecule must also be even according to the Nitrogen rule.
So from the Formula CHN, the nitrogen will have to be 2 because if we make use of 4, it will exceed the given M+ which is 80.
∴
C₄ = 4 × 12 = 48
H₄ = 4 × 1 = 4
N₂ = 2 × 14 = 28
80
As such, the molecular formula of the compound is C₄H₄N₂
Select the correct answer.
What is the solution to the problem expressed to the correct number of significant figures?
(102,900 ÷ 12) + (170 × 1.27) = ?
Suppose an element has two naturally occurring isotopes
42
X
20
44
X
20
with atomic masses 42.00 amu and 45.00 amu, respectively. Determine the percent abundance of the
45
X
20
isotope given an average atomic mass of 43.22 amu.
Answer:
Chlorine
Chlorine has two naturally occurring isotopes. In a sample of chlorine, 75.77% of the atoms are Cl-35, with a mass of 34.97amu.
Explanation:
hope it helps thanks❤
Chlorine has two naturally occurring isotopes. In a sample of chlorine, 75.77% of the atoms are Cl-35, with a mass of 34.97amu.
How do you calculate the atomic mass in percentage by isotopes?
List the known and unknown values and edit the problem. Convert each percentage value into a decimal by dividing it by 100. Multiply this number by the atomic mass of that spot. Mix together each isotope to find the median atomic mass.
How do you get the maximum amount of two isotopes?To calculate the maximum percentage of each isotope in a sample of something, chemists usually divide the atomic number of a particular isotope by the total number of atoms of all that isotope and multiply the result by 100.
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0-17, an isotope of oxygen, has 9 neutrons. The
of oxygen is 8.
isotope number
atomic number
mass number
atomic mass
Answer:
atomic number
Explanation:
The mass number (A) of an element is obtained by summing the number of neutrons and protons (nucleons) in the atom of that element. However, the proton number of an element is its atomic number (Z). Hence, it can be said that:
mass number = no. of neutrons + atomic number/number of protons.
According to this question, an isotope of oxygen is said to have a mass number of 17. If the neutron number of this isotope is given as 9, then this means that its ATOMIC NUMBER or no. of protons of that isotope is (17 - 9) = 8.
Answer:
atomic number
Explanation:
One of the nuclides in spent nuclear fuel is U-235, an alpha emitter with a half-life of 703 million years. How long will it take for an amount of U-235 to reach 23.0% of its initial amount
Answer:
1.49 × 10⁹ years
Explanation:
Step 1: Calculate the rate constant (k) for the nuclear decay of U-235
The decay follows first-order kinetics with a half-life (t1/2) of 703 × 10⁶ years. We can calculate "k" using the following expression.
k = ln2/ t1/2 = ln2 / 703 × 10⁶ y = 9.86 × 10⁻¹⁰ y⁻¹
Step 2: Calculate the time elapsed (t) so that the final amount ([U]) is 23.0% of the initial amount ([U]₀)
For first order kinetics, we will use the following expression.
ln ([U]/[U]₀) = -k × t
ln (0.230[U]₀/[U]₀) = -9.86 × 10⁻¹⁰ y⁻¹ × t
ln 0.230 = -9.86 × 10⁻¹⁰ y⁻¹ × t
t = 1.49 × 10⁹ y
1. Explain why food lasts longer when placed in the refrigerator as opposed to on the counter in the kitchen.
2. List and describe four factors that affect the rate of a reaction.
3. Sketch a potential energy diagram for the following reaction: N2(g)+3H2(g)-->2NH3(g)
Use Table I in the Chemistry Reference Table to identify the following on your graph: potential energy of reactants, potential energy of products, activation energy, and heat of reaction. State the value of the enthalpy and whether the reaction is endothermic or exothermic. Label the y-axis and potential energy and x-axis as reaction coordinate.
4. Describe and explain the effect of (a) the increase in temperature, (b) the increase in concentration of C2H4, and (c) a decrease in pressure to the following system at equilibrium: 2C + 2H2 + heat ⇌ C2H4
It last longer because it slows down the spread of bacteria.
Temperature, concentration, particle size, use of a catalyst.
What are the characteristics of an acid-base neutralization reaction?
the empirical formula of a compound is CH2 N2 and its molecular mass is 126.0. what is the molecular formula of the compound
Step 1: Represent a molecular formula.
[tex]\text{molecular formula} = (\text{CH}_{2}\text{N}_{2})_{n}[/tex]
Step 2: Calculate the empirical mass.
empirical mass = (12.0 g/mol × 1) + (1.0 g/mol × 2) + (14.0 g/mol × 2)
empirical mass = 42.0 g/mol
Step 3: Divide the molecular mass by the empirical mass.
[tex]n = \frac{\text{molecular mass}}{\text{empirical mass}}[/tex]
[tex]n = \frac{\text{126.0}}{\text{42.0}}[/tex]
[tex]n = 3[/tex]
Step 4: Multiply the subscripts by the value of n to obtain the molecular formula.
[tex]\text{molecular formula} = (\text{CH}_{2}\text{N}_{2})_{3}[/tex]
[tex]\boxed{\text{molecular formula} = \text{C}_{3}\text{H}_{6}\text{N}_{6}}[/tex]
[tex]\\[/tex]
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Which best describes how the total mass of the substances that go into
photosynthesis compares to the mass of substances that are present
afterward?
O A. The mass increases because the molecules that are produced are
larger than those that are used.
B. The mass increases because some light energy changes into
mass.
O C. The mass stays the same because the total number of atoms
does not change
O D. The mass decreases because plants destroy some of the atoms
during photosynthesis.
Answer:
C. The mass stays the same because the total number of atoms does not change
Explanation:
According to the law of conservation of matter/mass, matter cannot be created nor destroyed, hence, the amount of matter in the reactants must be the same amount in the products.
Using the photosynthetic reaction as a case study, carbon dioxide (CO2) and water (H2O) are the compounds that go into the reaction (reactants) while glucose and oxygen (O2) are the products of the reaction.
Using the law of conservation of matter to explain, the total mass of both the reactants and products stays the same because the total number of atoms does not change i.e. if 6 atoms of Carbon starts the reaction, 6 atoms of carbon will end it.
What is Markanikov rule?
Answer:
Regla de Markovnikov En fisicoquímica orgánica, la regla de Markovnikov es una observación respecto a la reacción de adición electrófila.Regla de Markovnikov En fisicoquímica orgánica, la regla de Markovnikov es una observación respecto a la reacción de adición electrófila.
Explanation:
Desclony When Fe(NO3)2 dissolves in water, what particles are present in the solution?
Answer:
hjfhgjgjgjghgjgjhgjhhjh
____________ can increase the presence of 5HT in the terminal button or synaptic cleft.
Answer:
Selective serotonin reuptake inhibitors (SSRIs)
Explanation:
A synaptic cleft is a space that separates two neurons thereby forming a junction between two or more neurons. The synaptic cleft helps in the transfer of nerve impulse from one neuron to the other.
5-HT is found in the enteric nervous system located in the gastrointestinal tract and it helps in modulating cognition, memory, sleep, and numerous physiological processes.
Selective serotonin reuptake inhibitors (SSRIs), such as fluoxetine and citalopram are used to increase the level of 5-HT in the synaptic cleft by inhibiting its reuptake into the presynaptic terminal.
Kavitha was doing an experiment to find out the percentage of water absorbed by the soil. She observed that soil 'sample A' absorbed more water compared to soil 'sample B'. If soil sample B is loamy soil, sample A contains which type of soil ?
{Note :- this question contains 2 points so please type the answer in a " short answer " type question
Answer:
Clay soil
Explanation:
We were told in the question about two samples of soil A and B. Sample B was confirmed to be loamy soil but it was discovered that sample A absorbed more water than sample B.
We now have to think about the kind of soil that has the greatest ability to absorb water. That soil type is called clay soil.
Clay soils possess a large surface area which is responsible for its ability to absorb more water. Hence, clay soil has the greatest water holding capacity.
1. As you go across a period, what is a useful comparison point?
A.
oxides
B.
halides
C.
hydrides
D.
hydroxides
-----
2. Most elements are
A.
allotropes
B.
nonmetals
C.
metalloids
D.
metals
----
3. A metalloid is a(n) __ conductor of heat and electricity than a metal.
A.
better
B.
worse
C.
equal
D.
cannot be determined
-----
4. What causes the formation of allotropes?
A.
pressure
B.
light
C.
temperature
D.
all of the above
----
As you move __and __ elements become more metallic.
A.
left, down
B.
right, down
C.
right, up
D.
left, up
------
5. All of the following metalloids form allotropes except
A.
B
B.
Si
C.
Te
D.
Po
------
6. What is a chemical property of a metal?
A.
malleable
B.
ductile
C.
positive oxidation states
D.
conducts heat and electricity
----
Explanation:
1. As you go across a period, what is a useful comparison point?
A.
oxides
2. Most elements are
A.
allotropes
3. A metalloid is a(n) __ conductor of heat and electricity than a metal.
A.
better
4. What causes the formation of allotropes?
A.
pressure
As you move __and __ elements become more metallic.
A.
left, down
5. All of the following metalloids form allotropes except
A.
B
6. What is a chemical property of a metal?
A.
malleable
Identify the conjugate acid/base pairs in each of the following equations:
(a) H2S + NH3 ⇔ NH4+ + HS-
Pair 1: H2S and
Pair 2: NH3 and
(b) HSO4- + NH3 ⇔ SO42- + NH4+
Pair 1: HSO4- and
Pair 2: NH3 and
(c) HBr + CH3O- ⇔ Br- + CH3OH
Pair 1: HBr and
Pair 2: CH3O- and
(d) HNO3 + H2O → NO3- + H3O+
Pair 1: HNO3 and
Pair 2: H2O and
Answer:
(a) Pair 1: H₂S and HS⁻
Pair 2: NH₃ and NH₄⁺
(b) Pair 1: HSO₄⁻ and SO₄⁻
Pair 2: NH₃ and NH₄⁺
(c) Pair 1: HBr and Br⁻
Pair 2: CH₃O⁻ and CH₃OH
(d) Pair 1: HNO₃ and NO₃⁻
Pair 2: H₃O⁺
Explanation:
When an acid loses its proton (H⁺), a conjugate base is produced.
When a base accepts a proton (H⁺), it forms a conjugate acid.
(a) H₂S is an acid. When it loses a proton, it forms the conjugate base HS⁻.
NH₃ is a base. When NH₃ gains a proton, it forms the conjugate acid NH₄⁺
(b) The acid HSO₄⁻ loses a H⁺ ion and forms the conjugate base SO₄²⁻.
The base NH₃ accepts a H⁺ ion to form the conjugate acid NH₄⁺.
(c) HBr is an acid. When loses the H⁺ ion, it forms the conjugate base Br⁻.
CH₃O⁻ accepts a H⁺ ion to form the conjugate acid CH₃OH.
(d) HNO₃ loses a proton to form the conjugate base NO₃⁻.
H₂O gains a proton to form the conjugate acid H₃O⁺.
g Ions B and C react to form the complex BC. If 35.0 mL of 1.00 M B is combined with 35.0 mL of 1.00 M C, 0.00500 mol of BC is formed. Determine the equilibrium constant for this reaction.
Answer:
Kf = 0.389.
Explanation:
Hello there!
In this case, it turns out possible for us to solve this problem by firstly writing the equilibrium chemical equation and equilibrium expression for the formation of this complex:
[tex]B+C\rightleftharpoons BC\\\\Kf=\frac{[BC]}{[B][C]}[/tex]
Thus, we firstly calculate the concentrations at equilibrium, knowing that the reaction extent in this case is 0.00500mol (same as the formed moles of BC):
[tex][B]=[C]=\frac{0.0350L*1.00mol/L-0.00500mol}{0.0700L} =0.429M[/tex]
[tex][BC]=\frac{0.00500mol}{0.0700L} =0.0714M[/tex]
And finally, the equilibrium constant:
[tex]Kf=\frac{0.0714}{[0.429][0.429]}\\\\Kf=0.389[/tex]
Regards!
the total pressure in a mixture of gases is equal to the partial pressures of
Answer:
"The total pressure in a mixture of gases is equal to the sum of partial pressures of each gas"
Explanation:
Dalton's law of partial pressures state that, in a mixture of gases, the total pressure is equal to the sum of the partial pressure exerted by each gas of the mixture. The equation is:
Total pressure = Partial pressure Gas 1 + Partial pressure Gas 2 + .... + Partial pressure Gas n
To complete the sentence we can say:
"The total pressure in a mixture of gases is equal to the sum of partial pressures of each gas"
Considering the Dalton's partial pressure, the total pressure in a mixture of gases is equal to the sum of partial pressures of each gas.
The pressure exerted by a particular gas in a mixture is known as its partial pressure. So, Dalton's law states that the total pressure of a gas mixture is equal to the sum of the pressures that each gas would exert if it were alone:
[tex]P_{T} =P_{A} +P_{B}[/tex]
This relationship is due to the assumption that there are no attractive forces between the gases.
Dalton's partial pressure law can also be expressed in terms of the mole fraction of the gas in the mixture. The mole fraction is a dimensionless quantity that expresses the ratio of the number of moles of a component to the number of moles of all the components present.
So in a mixture of two or more gases, the partial pressure of gas A can be expressed as:
[tex]P_{A} =x_{A} P_{T}[/tex]
In summary, the total pressure in a mixture of gases is equal to the sum of partial pressures of each gas.
Learn more:
https://brainly.com/question/14239096?referrer=searchResultshttps://brainly.com/question/25181467?referrer=searchResultshttps://brainly.com/question/14119417The general formula for ____________ and ____________ are CnH2n+2 and CnH2n , respectively. Axial and equatorial hydrogen atoms are interconverted during a ____________ . The anti conformation is ____________ in energy than a gauche conformation. The increase in energy when tetrahedral bond angles deviate from the optimum angle of 109.5° is known as ____________ strain. The ____________ position has more room than the ____________ position, so larger substituents are more stable in the equatorial position.
Answer:
Alkanes
Cycloalkanes
Ring flip
Lower
Angle
Equatorial
Axial
Explanation:
For alkanes, the general molecular formula is CnH2n+2 while for cycloalkanes, the general molecular formula is CnH2n.
The cycloalkanes could undergo a ring flip in which axial and equatorial hydrogen atoms are interconverted.
The lower energy conformation of alkanes is the anti conformation and not the gauche conformation due to steric strain.
When the bond angle in alkanes deviate from the ideal 109.5°, an angle strain has occurred.
For bulky groups, the equatorial position his preferred since it has more room than the axial position.
How many milliliters of a 6.00 M NaCl solution are needed to make 250.0 milliliters of a 0.500 M NaCl solution?
Answer:
20,8ml NaCl 6M
Explanation:
C1V1 = C2V2
Draw the Lewis structure of NCl3NCl3 . Include lone pairs. Select Draw Rings More Erase Select Draw Rings More Erase Select Draw Rings More Erase Select Draw Rings More Erase Select Draw Rings More Erase Select Draw Rings More Erase Select Draw Rings More Erase Select Draw Rings More Erase Select Draw Rings More Erase Select Draw Rings More Erase Select Draw Rings More Erase Cl N
Answer:
See explanation and image attached
Explanation:
Nitrogen trichloride NCl3 contains one nitrogen and three chlorine atoms. Each chlorine atom has three lone pairs of electrons while nitrogen has one lone pair of electrons.
The molecule geometry of the molecule is trigonal pyramidal while it's electron domain geometry is tetrahedral. Nitrogen is the central atom and is found in sp3 hybridization.
There is no formal charge on the molecule.
why is it preferred to use calcium oxide rather than calcium chloride in preparation of iron (III) chloride
Answer:
Calcium Oxide is a drying agent, hence it dehydrates the reaction to give pure solid Iron ( III ) chloride, which cannot be done by calcium chloride.
It preferred to use calcium oxide rather than calcium chloride in preparation of iron (III) chloride because Calcium Oxide is a drying agent, hence it dehydrates the reaction to give pure solid Iron ( III ) chloride, which cannot be done by calcium chloride.
What is Dehydration ?A process such as a chemical reaction that removes water.The atoms which constitute the molecule of water that is removed.
Hence,It preferred to use calcium oxide rather than calcium chloride in preparation of iron (III) chloride because Calcium Oxide is a drying agent,
Thus, it dehydrates the reaction to give pure solid Iron ( III ) chloride, which cannot be done by calcium chloride.
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(NH4)2SO4(aq)+SrCl2(aq)→
What does the rate law tell you about a reaction?
A. How the concentration of the reactants affects the rate of a
reaction
B. How temperature affects the rate of a reaction
C. How the equilibrium constant is related to the rate of a reaction
D. How the rate of a reaction affects the total time of a reaction
Answer:
A. How the concentration of the reactants affects the rate of a reaction
Explanation:
Let's consider a generic reaction.
A + B ⇒ Products
The generic rate law is:
rate = k × [A]ᵃ × [B]ᵇ
where,
rate: rate of the reaction[A] and [B]: molar concentrations of the reactantsk: rate constanta and b: reaction ordersAs we can see, the rate law shows how the concentration of the reactants affects the rate of a reaction.
điện phân nóng chảy hoàn toàn 14,9 gam muối clorua của 1 kim loại kềm R thu đc 2,24 lít khí . R là kim loại gì ?
Answer:
d
Explanation:
nCl2 = 0,1 -> nRCI = 0,2
M muéi = R + 35,5 = 14,9/0,2
-> R = 39: R la K
Answer:
d
Explanation:
nCl2 = 0,1 -> nRCI = 0,2
M muéi = R + 35,5 = 14,9 / 0,2
-> R = 39: R la K
