Answer:
On moving from left to right in a period the electropositive character decreases as the tendency to lose electrons decreases.
Explanation:
A(n) _____, used as part of the stationary phase, has an affinity for the solvent and the chemical components of the mixture. adsorbent eluent Rf factor chromatogram
The Adsorbent is used as part of the stationary phase and has an affinity for the solvent and the chemical components of the mixture.
The adsorbent has a high affinity for solvent and the chemical components of the mixture.
Chromatography is a method of separation in which the mixture of substances is introduced into a mobile phase (solvent). The separation occurs as the solvent interacts with an adsorbent(stationary phase).
The extent of separation of the components of the mixture depends on the extent of interaction between the mobile and the stationary phase . This interaction also determines the retention factor (Rf) of the separation.
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HELP! A man makes breakfast. He puts some toast in the toaster, and mixes some eggs with a little milk in a bowl. As he begins cooking the eggs, he smells the toast burning. He takes the toast out of the toaster and puts some butter on it, which melts. Finally, he pours some orange juice through a strainer to remove the pulp. He eats the meal, and he digests it as he drives to work in his car.
A. Which option correctly identifies a chemical and a physical change in the scenario?
B. Burning toast is a chemical change; straining orange juice is a physical change.
C. Digesting food is a physical change; the car burning gas is a chemical change.
D. Burning toast is a physical change; straining orange juice is a chemical change.
Digesting food is a chemical change; the car burning gas is a physical change.
Answer:B. Burning toast is a chemical change; straining orange juice is a physical change.
Explanation:
A Physical change Is a type of change on a substance that does not affect its composition but can only change the appearance of the substance.
While
A Chemical changes is one that changes the substance to an entirely new substance.
Now 1. Burning toast is a chemical change, This is because First, Burning is a chemical reaction on its own . The toast also is a different substance from the white bread itself to a brown substance .
2. Straining orange juice is a physical change because no new substance is being formed only a SEPARATION of the orange pulp from the juice.
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We have that Burning toast is a chemical change; straining orange juice is a physical change.
The correct option is Option B
Physical change
This Refers to a change to the Physical Characteristics of a substance
While
Chemical change is a change Chemical Characteristics of a substance
and
Physical changes tends to undergo reversible processes while
chemicals do not
Therefore
The correct option is Option B
Burning toast is a chemical change; straining orange juice is a physical change.
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uses of rare or inert gases
Explanation:
noble gases are useful let's take for instance helium which is used in balloons. they are used to form inert atmosphere and they are used also to deter chemical reaction.
20. Stoichiometry is based on
A. molecular weight.
B. temperature.
C. conservation of matter.
D. pressure.
Answer:
The correct option is (c)
Answer:
the law of conservation of mass
An ice cube, measured at 260 Kelvin, is dropped into a cup of tea that is 350 Kelvin. The temperature of the tea is recorded every 30 seconds and shows the temperature dropping for 4 minutes. After 4 minutes the temperature stays steady at 300 Kelvin. What is this called?
A. Thermal equilibrium
B. Specific heat capacity
C. Latent heat
D. Temperature transfer
Answer:
Specific Heat Capacity
A sample of water at 21.5°C required an input of 1.69 x 104 of heat to reach its boiling point, 100.0 °C. What was the mass of the
water?
The color cyan has a frequency of 5.902x10^14 What is the wavelength in nm ? Record your answer with 2
decimals.
The wavelength of the color cyan is 508 nm.
To solve the problem, we use the following equation that relates the frequency (ν) and the wavelength (λ) of a wave:
c = λ x ν
Given:
c = speed of light = 3.00 x 10⁸ m/s (is a constant)
ν = 5.902 x 10¹⁴ Hz = 5.902 s⁻¹
We introduce the data to calculate the wavelength in m:
λ = c/ν = (3.00 x 10⁸ m/s)/(5.902 s⁻¹) = 5.08 x 10⁻⁷ m
We know that 10⁻⁹m = 1 nm, so we convert λ to nm:
λ = 5.08 x 10⁻⁷ m x 1 nm/10⁻⁹m = 508 nm
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Flowers are vascular plants.
Vascular plants have
structures
that transport nutrients
and water within a plant.
A. ball-like
B. heart-like
C. box-like
D. tube-like
Answer:
I think tube like ... is it right
Answer:
The actual answer is flowers have heart like structures that transport nutrients and water with in the plants.
I 100 mL o a pharmaceutical preparation contains 20 mL o a 50% w/v solution o benzalkonium chloride, what is the percent strength o that agent in the solution
The percentage strength of the agent is 10 %
Since 100 mL of a pharmaceutical preparation contains 20 mL of a 50% w/v solution of benzalkonium chloride, we desire to find the percentage strength of that agent in the 100 mL solution.
Let C₁ = percentage strength of 20 mL solution = 50 %, V₁ = initial volume = 20 mL, C₂ = percentage strength of agent in 100 mL solution and V₂ = final volume = 100 mL.
Since the initial quantity of agent in 20 mL solution equals the final quantity of agent in 100 mL solution, we have that
C₁V₁ = C₂V₂
So, making C₂ = percentage strength of agent in 100 mL solution the subject of the formula, we have
C₂ = C₁V₁/V₂
Substituting the values of the variables into the equation, we have
C₂ = C₁V₁/V₂
C₂ = 50 % × 20 mL/100 mL
C₂ = 50 % × 0.2
C₂ = 10 %
So, the percentage strength of the agent is 10 %.
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What does X represent in the following reaction?
239 239
93NP → 94Pu + X
A) a neutron
C) an alpha particle
B) a proton
D) a beta particle
Answer:
D. beta particle
Explanation:
Pu has 94 protons which is only one more than Np (93), that means beta decay. Atomic mass stays the same in beta decay. Beta is very small particle so atomic mass stays at 239.
The given reaction is an example of beta decay where the atomic number of the nuclei increases by one unit and mass number remains unchanged. Therefore, the particle X is a beta particle or an electron.
What is beta decay?Heavy unstable isotopes of atoms undergoes nuclear decay by the emission of charged particles such as alpha or beta particle. In alpha decay, the helium nuclei is emitted and in beta decay, electrons are emitted.
In alpha decay, the mass number of the nuclei decreases by 4 units and atomic number by 2 units. In beta decay, the mass number does not change but the atomic number increases by one unit.
Neptunium undergoes beta decay and forms the plutonium nuclei. Thus X is a beta particle. The reaction is written as follows:
[tex]\rm _{93} ^{239}Np \rightarrow _{94}^{239}Pu + _{-1}^{0}e[/tex]
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Someone help please I don’t know the answer to the question I meeed help
Answer: 143.3
137+115+104+263+98 divided by 5.Which gives us 143.3
What will be the new volume if the temperature remain constant ? The pressure on 2.50L of anaesthetic gas is change from 760mm Hg to 304mm Hg.
Answer:
[tex]\boxed {\boxed {\sf 6.25 \ L}}[/tex]
Explanation:
We are asked to find the new volume given a change in pressure. Since the temperature remains constant we are only concerned with volume and pressure. We will use Boyle's Law, which states the volume of a gas is inversely proportional to the pressure. The formula for this law is:
[tex]P_1V_1= P_2V_2[/tex]
Initially, the volume of the gas is 2.50 liters and the pressure is 760 millimeters of mercury.
[tex]760 \ mm \ Hg * 2.50 \ L = P_2V_2[/tex]
The pressure is changed to 304 millimeters of mercury, but the volume is unknown.
[tex]760 \ mm \ Hg * 2.50 \ L = 304 \ mm \ Hg * V_2[/tex]
We are solving for the new volume so we must isolate the variable V₂. It is being multiplied by 304 millimeters of mercury. The inverse operation of multiplication is division. Divide both sides by 304 mm Hg.
[tex]\frac {760 \ mm \ Hg * 2.50 \ L }{304 \ mm \ Hg}= \frac{304 \ mm \ Hg * V_2}{304 \ mm \ Hg}[/tex]
[tex]\frac {760 \ mm \ Hg * 2.50 \ L }{304 \ mm \ Hg}= V_2[/tex]
The units of millimeters of mercury cancel out.
[tex]\frac {760 * 2.50 \ L }{304 }= V_2[/tex]
[tex]\frac {1900}{304} \ L =V_2[/tex]
[tex]6.25 \ L =V_2[/tex]
The new volume of the anesthetic gas after the change in pressure is 6.25 liters.
What is the maximum number of electrons in the following energy level?
n = 4
Answer: 32 electrons
Explanation:
Explain why it is not advisable to add water to acid when
mixing them
Answer:
Consequence
you form an extremely concentrated solution of acid initially.and the solution may boil very violently, splashing concentrated acid. I hope this helped! :)How does distance between two objects affect their gravitational force? (2 points)
a
Force increases as distance increases.
b
Force decreases as distance increases.
c
Force decreases as distance decreases.
d
Force is not related to distance.
Answer:
Option B: as the distance between the objects increases the Force of gravity decreases
Carbonic acid (H₂CO₃) is a polyprotic acid. When carbonic acid dissolves in water, which is higher, the concentration of HCO₃- ions or the concentration of CO₃²- ions?
Please explain!
The concentration of CO₃²⁻ ions will be higher
To explain, I want you to imagine H₂CO₃ in water.
we know that it will lose 2 of it's protons, and form 2 ions
The ion which is more stable will have a higher concentration because that ion will refuse to react with anything else, so once something turns into that specific ion, it's not going back... unless there's a more stabler ion possible
In this case, the 2 ions formed are: HCO₃⁻ and CO₃⁽²⁻⁾, drawing the structures of both the ions tells us that both of them have resonance, but the CO₃⁽²⁻⁾ ion has more resonance structures and hence is more stable
A sample of oxygen gas at a pressure of 1.19 atm and a temperature of 24.4 °C, occupies a volume of 18.7 liters. If the gas is allowed to expand at constant temperature to a volume of 29.4 liters, the pressure of the gas sample will be ______ atm.
Answer:
[tex]\boxed {\boxed {\sf 0.757 \ atm}}[/tex]
Explanation:
We are asked to find the pressure of a gas given a change in volume. Since the temperature remains constant, we are only concerned with volume and pressure. We will use Boyle's Law, which states the volume is inversely proportional to the pressure. The formula for this law is:
[tex]P_1V_1= P_2V_2[/tex]
Initially, the oxygen gas occupies a volume of 18.7 liters at a pressure of 1.19 atmospheres.
[tex]1.19 \ atm * 18.7 \ L = P_2V_2[/tex]
The gas expands to a volume of 29.4 liters, but the pressure is unknown.
[tex]1.19 \ atm * 18.7 \ L = P_2 * 29.4 \ L[/tex]
We are solving for the new pressure, so we must isolate the variable [tex]P_2[/tex]. It is being multiplied by 29.4 liters. The inverse operation of multiplication is division. Divide both sides of the equation by 29.4 L.
[tex]\frac {1.19 \ atm * 18.7 \ L}{29.4 \ L} =\frac{ P_2 * 29.4 \ L}{29.4 \ L}[/tex]
[tex]\frac {1.19 \ atm * 18.7 \ L}{29.4 \ L} =P_2[/tex]
The units of liters cancel.
[tex]\frac {1.19 \ atm * 18.7 }{29.4 } =P_2[/tex]
[tex]\frac {22.253}{29.4 } \ atm = P_2[/tex]
[tex]0.7569047619 \ atm =P_2[/tex]
The original measurements all have 3 significant figures, so our answer must have the same. For the number we calculated, that is the thousandth place. The 9 in the ten-thousandth place to the right of this place tells us to round the 6 up to a 7.
[tex]0.757 \ atm \approx P_2[/tex]
The pressure of the gas sample is approximately 0.757 atmospheres.
According to Boyle's law, for a given mass of ideal gas, pressure of gas is inversely proportional to the volume of gas, Provided the Temprature remains constant.
P₁ = 1.19 atmP₂ = ?V₁ = 18.7 LV₂ = 29.4 LT = constant = 24.4° C = Isothermal process[tex]\implies \sf P_1 V_1 = P_2 V_2 \\ [/tex]
[tex]\implies \sf 1.19 \times 18. 7= P_2 \times 29.4 \\[/tex]
[tex]\implies \sf 22.253= P_2 \times 29.4 \\[/tex]
[tex]\implies \sf P_2 = \dfrac{22.253}{29.4} \\[/tex]
[tex]\implies \underline{ \red{\boxed{ \bf P_2 \approx0.756 \: atm }}} \\[/tex]
c. Which substance has a density of 7.87 g/cm3?
An ion of a single pure element always has an oxidation number of ________.
A. None of these
B. magnitude equal to its atomic number
C. 1
D. 0
Answer:
0
Explanation:
pure elements will always possess an oxidation number of 0, regardless of their charge.
Answer:
D.) 0
Explanation:
I got it correct on founders edtell
How would you expect cesium, Cs, to react with water? explaining your reasoning.
Answer:
Caesium reacts rapidly with water to form a colourless basic solution of caesium hydroxide (CsOH) and hydrogen gas (H2).
Explanation:
The reaction continues even when the solution becomes basic. The resulting solution is basic because of the dissolved hydroxide. The reaction is exothermic.
What mass of water is formed in the reaction of 4.16g H with excess oxygen gas.
Answer:
Explanation:
Start with a balanced equation.
2H2 + O2 → 2H2O
Calculate mole H2 using the formula: n = m/M, where:
n = mole
m = mass (g)
M = molar mass (g/mol)
Calculate molar mass of H2.
M H2 = 2 × 1.008 g/mol = 2.016 g/mol
Calculate moles H2.
n H2 = 4.16 g H2/2.016 g/mol = 2.063 mol H2
Calculate moles H2O by multiplying moles H2 by the mole ratio between H2O and H2 from the balanced equation, so that moles H2 cancel.
2.063 mol H2 × (2 mol H2O/2 mol H2) = 2.063 mol H2O
The mass of water will be calculated by rearranging the n = m/M formula to isolate m;
m = n × M
Calculate the molar mass H2O.
M H2O = (2 × 1.008 g/mol) + (1 × 15.999 g/mol) = 18.015 g/mol
Calculate the mass H2O.
m = n × M = 2.063 mol H2O × 18.015 g/mol = 37.2 g H2O
4.16 g H2 with excess O2 will produce 37.2 g H2O.
Name the alkyne. Spelling and punctuation count.
The name of a compound is determined by IUPAC nomenclature
The International Union of Pure and Applied Chemistry have designated a universal rule for the nomenclature of organic compounds generally known as IUPAC nomenclature.
The whole idea of the IUPAC nomenclature is to have a universally agreed pattern of naming organic compounds according to their structure.
The compound is always named in such a way that the substituents and the functional group receives the lowest number.
In this case, the functional group is alkyne hence the name of the compound ends in -yne. The methyl group is substituted on position four.
Putting all these together the compound should be named as; 4-methylhept-2-yne
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The following two compounds each exhibit two heteroatoms (one nitrogen atom and one oxygen atom). In compound A, the lone pair on the nitrogen atom is more likely to function as a base. However, in compound B, the lone pair on the oxygen atom is more likely to function as a base. Explain this difference by selecting the correct reason(s)
Answer:
The answer is the photo attached
Explanation:
Để xác định hàm lượng Cu trong hợp kim Cu-Zn người ta làm như sau: Hòa
tan hoàn toàn 2,068g mẫu hợp kim Cu-Zn trong lượng dư axit HNO3, thu được dung
dịch X. Đun đuổi axit dư, điều chỉnh tới pH 3 thu được 100mL dung dịch Y. Lấy
10mL dung dịch Y, thêm KI dư, rồi chuẩn độ dung dịch tạo thành bằng dung dịch
Na2S2O3 0,1M thì thấy hết 15,0 mL. Viết các phương trình phản ứng xảy ra. Tính
hàm lượng Cu trong mẫu hợp kim trên.
Which side of the chain should you count from when naming organic compounds?
Center
Right side
Left side
Side that will give you the longest Carbon chain
Side that will give you the longest carbon chain will be counted when naming organic compounds.
What is an Organic compound?These are chemical compounds that contain carbon-hydrogen or carbon-carbon bonds in their structure.
The longest carbon chain should be counted first to ascertain the type of compound to be named.
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What is Entropy?
A. The opposite of Enthalpy
B. The temperature at which a reaction is feasible.
C. A measure of disorder.
D. Free energy used for a reaction.
Answer:
C. A measure of disorder :)
what is the bond energy required to break one mole of carbon-carbon bonds
Answer:
100 kcal of bond energy
Chad drew a diagram to compare animal cells and bacterial cells.
Which label belongs in the area marked X?
Explanation:
Don't know wwwwmkbnkkkoo
Why benzene is called aromatic compound according to Huckel’s rule?
Answer:
It obeys rule
Explanation:
Benzene is an aromatic hydrocarbon because it obeys Hückel's rule.
Answer:
Benzene is an aromatic compound because it is planar, cyclic, conjugated and has (4n +2) π electrons, where n= 1.
Explanation:
Hückel's rule states that a molecule is aromatic if it is planar, cyclic, conjugated and has (4n +2) π electrons.
Breaking it down into 4 requirements, we have:
planarcyclicconjugated(4n +2) π electronsLet's look at each of the 4 parts!
What is planar?
Planar refers to the molecule being flat. When an atom is sp² hybridized, it is in a trigonal planar geometry. Let's look at the benzene molecule. Each carbon is attached to 3 other atoms, namely 2 carbons and 1 hydrogen. This means that each carbon is sp² hybridized, making the molecule planar.
Cyclic
This refers to the molecule having a closed ring shape. Benzene fulfils this criteria.
Conjugation
This refers to a system of connected p orbitals, which allows π electrons to delocalize. Each carbon atom in benzene has one 2p orbital, making benzene a conjugated molecule. For molecules that are not cations or anions, conjugated molecules are those that have alternating single and double bonds.
(4n +2) π electrons
n is an integer (e.g. 0, 1, 2, 3) thus for the molecule to be aromatic, it can have 2, 6 or 10 π electrons (non exhaustive). This separates an aromatic compound from an antiaromatic compound, which has 4n π electrons instead.
Benzene has 6 π electrons, so n has a value of 1 in this case.
Thus, benzene is an aromatic compound because it is planar, cyclic, conjugated and has (4n +2) π electrons.
_______
Counting the number of π electrons
Let's look at π bonds!
A double bond is made up of 1 σ bond and 1 π bond, and each π bond is made up of 2 π electrons. We do not count the number of single bonds since single bonds are made up of 1 σ bond only.
There are 3 double bonds in the Kekulé structure of benzene. Thus, the number of π electrons in benzene is 3(2)= 6.
Attached diagrams
Kekulé structure of benzenesp² hybridized carbon6 p orbitals in benzene ringhelp me in my hw,wt is physical change and chemical change Answer it asap plz don't spam
Answer:
Sorry but i don't undertsnad the question.
Explanation:
Answer:
A physical change is a change to the physical—as opposed to chemical—properties of a substance. They are usually reversible. The physical properties of a substance include such characteristics as shape, color, texture, flexibility, density, and mass.
A chemical change happens when one chemical substance is transformed into one or more different substances, such as when iron becomes rust.
Do u want examples ?
