Physical and chemical properties of each family different 'depend on valence electron'
The vertical columns on the periodic table are called groups or families because of their similar chemical behavior and all the members of a family of elements have the same number of valence electrons and similar chemical properties and isotopes of an element have same number of electron as an atom of that element but they have different number of neutron which affect the mass number and mass number determine the physical properties while atomic number determine the chemical properties
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Which statements explain why theories change over time? Check all that apply.
Scientists change the definition of theory to have their ideas accepted.
New information and technology may be developed that influence the theory.
Theories change with each new generation of scientists.
New experimental methods provide new information.
Theories may or may not be supported by new information.
The following are true about a theory;
New information and technology may be developed that influence the theory.New experimental methods provide new information.Theories may or may not be supported by new information.What is a theory?A theory is an explanation that is given to a phenomenon which may have some kind of underpinning reasoning that may not necessarily be empirical. Thus a theory has withstood some kind of scrutiny but is not yet absolutely accepted as true.
Thus the following are true about theory;
New information and technology may be developed that influence the theory.New experimental methods provide new information.Theories may or may not be supported by new information.Learn more about theory:https://brainly.com/question/1759635
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A 2.300 −g sample of quinone (C6H4O2) is burned in a bomb calorimeter whose total heat capacity is 7.854 kJ/∘C . The temperature of the calorimeter increases from 24.64 ∘C to 32.09 ∘C .What is the heat of combustion per gram of quinone?
The heat of combustion per gram of quinone is -25.43 KJ/g.
A constant-volume bomb calorimeter can be used to calculate a substance's heat of combustion. The heat absorbed by the bomb calorimeter can be compared to the heat emitted by the reaction. Additionally, it is necessary to understand the calorimeter's heat capacity.- Q(rxn) = Q(cal) = C(cal)ΔTGiven,
mass of sample = 2.300g
total heat capacity = 7.854 kJ/∘C
Temperature change = 32.09 - 24.64 = 7.45
we have to find out heat of combustion per gram of quinone.
- Q(rxn) = Q(cal) = C(cal)ΔT
Q(rxn) = -(7.854kJ/⁰C)(32.09 - 24.64)
= -58.5 KJ
Now, we will calculate heat of combustion per gram.
Q(rxn) = -58.5/2.3g = -25.43 KJ/g
negative sign denote exothermic reaction.
Thus, heat of combustion per gram of quinone is -25.43 KJ/g.
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A measurement was taken three times. The correct measurement was 68.1 mL. Circle whether the
set of measurements is accurate, precise, both, or neither.
a) 78.1 mL, 43.9 mL., 2 mL. accurate precise both or neither
b) 68.1 ml, 68.2 mL, 68.0 mL. accurate precise both or neither
c) 98.0 mL, 98.2 mL., 97.9 mL. accurate precise both or neither
d) 72.0 mL, 60.3 mL, 68.1 mL. accurate precise both or neither
Option B is the correct answer it is accurate, precise both .
How to find accuracy in a measurement ?Accuracy refers to how close average valve is to the actual valve.
a) Average of measured valve is far from the actual valve, so neither precise nor accurate.
b) Average valve = actual valve ,so it is precise as well as accurate.
c) Average of measured valve is far from the actual valve, so neither precise nor accurate .
d) Average valve is close to only measured valve, hence measurement is accurate but not precise.
Hence option B is correct .
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Why did the Netherlands replace Italy as the center of European finance in the seventeenth century?
The VOC started a phase of unprofitable growth. The Netherlands was able to participate as a significant power in the European wars at the turn of the 18th century by recruiting mercenary forces and supporting its allies because its financial strength proved to be more enduring.
Antwerp served as the commercial and financial hub of the Seventeen Provinces and Northwestern Europe. In the end, Antwerp played a significant role in the uprising against the Spanish Ha Amsterdam became one of the most significant commerce hubs in the world during the 17th century Dutch Golden Age. Money was brought about by trade, and along with wealth, the arts and sciences flourished. In the end, the city that joined was designated as the "capital" of the Dutch Revolt.
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Polyethylene is a polymer that is flexible and often used to make clear plastic wrap. How can this
polymer be changed to make it less flexible, stronger, and harder? (1 point)
O Cross-linking the layers of polyethylene using covalent bonds.
O Adding larger carbon atoms in between the layers to make them more stable.
O Shortening the length, the polymer so that it cannot bend as much.
O Changing the covalent bonds to ionic bonds, which are stronger.
Polyethylene polymer can be changed to make it less flexible, stronger, and harder by: (a) Cross-linking the layers of polyethylene using covalent bonds.
Polyethylene is the polymer extensively used to make plastic products. It is light, versatile and flexible substance. It can be made more stiff by introducing covalent bonds to form the cross-links between the layers. The more will be the cross-links between the layers, reduced will be the length of the polymer and hence the stiffness is increased while reducing the flexibility.
Covalent bonds are the strongest type of bonds formed by the sharing of electrons between two or more atoms. The sharing is mutual between the atoms and they do not much electronegativity difference between them.
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. Calculate the pH value of a solution in which [OH- ] = 1.49 × 10−8M
Answer:
The pH of the solution is 6.17.
Explanation:
To find the pH of the solution, we have to first calculate its pOH using the formula:
[tex]\boxed{\mathrm{pOH = - log_{10}[OH^-]}}[/tex]
Substituting the given value of [OH⁻] into the formula, we get:
[tex]\mathrm{pOH = -log_{10}(1.49 \times 10^{-8})}[/tex]
[tex]= \bf 7.83[/tex]
Now that we have the value of the pOH of the solution, we can find its pH using the following formula:
[tex]\boxed{\mathrm{pH + pOH = 14}}[/tex]
∴ [tex]\mathrm{pH} + 7.83 = 14[/tex]
⇒ [tex]\mathrm{pH } = 14 - 7.83[/tex]
⇒ [tex]\mathrm{pH } = \bf 6.17[/tex]
find the absolute and percent relative uncertainty
91.3 (+-1.0) mM * (40.3 (+-0.2) mL) / (21.1 (+-0.2) mL)
a. The percentage relative uncertainty is 1.1 %
b. The absoulte uncertainty is ± 1.9
a. How to calculate the percentage relative uncertainty?Since 91.3 (+-1.0) mM * (40.3 (+-0.2) mL) / (21.1 (+-0.2) mL) is in the form
R = A × B/C, the relative uncertainty is given by
ΔR/R = √[(ΔA/A)² + (ΔB/B)² + (ΔC/C)²] where
ΔA = ± 0.2 mMA = 91.3 mMΔB = ± 0.2 mLB = 40.3 mLΔC = ± 0.2 mLC = 21.1 mLSubstituting the values of the variables into the equation, we have
ΔR/R = √[(ΔA/A)² + (ΔB/B)² + (ΔC/C)²]
ΔR/R = √[(0.2 mM/91.3 mM)² + (0.2 mL/40.3 mL)² + (0.2 mL/21.1 mL)²]
ΔR/R = √[(0.002191)² + (0.004963)² + (0.009479)²]
ΔR/R = √[0.00000480 + 0.00002463 + 0.00008985]
ΔR/R = √0.00011928
ΔR/R = ± 0.0109
ΔR/R ≅ ±0.011
So, the percentage relative uncertainty % ΔR/R = ΔR/R × 100 %
= 0.011 × 100 %
= 1.1 %
So, the percentage relative uncertainty is 1.1 %
b. How to calculate the absolute uncertainty?Since R = A × B/C where
A = 91.3 mM, B = 40.3 mL and C = 21.1 mLSo, R = A × B/C
= 91.3 mM × 40.3 mL/21.1 mL
= 3679.39 mMmL/21.1 mL
= 174.38 mM
≅ 174.4 mM
Now, the absoulte uncertainty in R, ΔR = ΔR/R × R
= ±0.011 × 174.4 mM
= ± 1.92
≅ ± 1.9
So, the absoulte uncertainty is ± 1.9
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How can you separate a mixture of water, sand, pebbles, and paper clips?
Because the mixture's components are so dissimilar in terms of their sizes, forms, textures, and colors, the traditional method of handpicking might work best for separation.
To separate the sand from the grass and pebble mixture, use a sieve that is relatively fine (the one occasionally used in the kitchen will work well:)). Pebbles and grass will pass through the sieve without the sand.
Put the grass and pebble mixture in a beaker and add water. Based on variations in their densities, the process of sedimentation is used to distinguish grass, which floats at the top, from stones, which settle at the bottom. To restore the separated grass to its original condition, blow it dry.
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An unknown compound contains only carbon, hydrogen, and oxygen (C₂H₂O₂). Combustion of
4.50 g of this compound produced 6.60 g of carbon dioxide and 2.70 g of water.
How many moles of carbon, C, were in the original sample?
Express your answer to three significant figures and include the appropriate units.
The number of moles of carbon in the original sample is 0.15 moles.
Let the formula of compound be CaHbOc.
The reaction when this compound undergoes combustion is as follows,
CaHbOc + O2 = CO2 + H2O
We are given that 4.50 g of compound releases 6.60 g of CO2 and 2.70 g of H2O.
First we have to calculate the moles of CO2 and H2O by dividing the given mass by their molar mass.
Moles of CO2 = 6.60/44 = 0.15 moles
Moles of H2O = 0.15 moles
The mass of carbon in CO2 = 0.15 x 12 = 1.80 g
The mass of carbon in CO2 is equal to the mass of carbon in the original sample.
Therefore, the number of moles of carbon in the original sample is 0.15 moles.
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1. How is energy being used inefficiently?
2.What should you do to make it efficient?
pls answer thank you :)
Answer:
1. Energy intensity (primary energy consumption divided by GDP) for the world and various countries. The lower the value, the less energy is used to generate economic output, so lower means more efficient in a sense.
2.Lower Your Thermostat. Adopt the habit of lowering the temperature on your thermostat while away from home.
Start a Compost Pile.
Install Low-Flow Showerheads.
Seal All Windows.
Limit Space Heater Use.
Turn Off Unnecessary Water.
Replace Incandescent Bulbs.
Unplug Unused Chargers.
nononononononononononon
Answer:
Explanation:
yesyesyesyesyesyesyesyesyes
Use the periodic table to predict which ion will form from each main-group element.
Na:
F:
N:
I:
Sr:
The ions that are formed by the ions is;
Na^+F^-N^3-I^-Sr^2+What is an ion?The term ion refers to a specie that is obtained by the loss or gain of electrons. A positive ion is formed by the loss of electrons while a negative ion is formed by gain of electrons.
A positive ions has more protons than electrons while a negative ion has more electrons than protons. There is only one major ion that could be formed by main group elements.
The ions that are formed by the ions is;
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Inverse relationship
No relationship
Linear relationship
what happens when you mix water and powdered juice together and how di you make it?
Answer: the powdered juice dissolves
Explanation: powdered juice is completely dissolved in water making it present in all the water
What volume (in L) of 1.50 M Na₂CO₃ would be required to obtain 0.650 moles of Na⁺ ions?
The Volume of Na₂CO₃ solution required to obtain 0.650 moles of Na⁺ ions is 216 mL.
What is the number of moles sodium ions produced by the dissociation of 1 mole of Na₂CO₃?The number of moles sodium ions produced by the dissociation of 1 mole of Na₂CO₃ is determined from the dissociation equation of Na₂CO₃ given below:
Na₂CO₃ (aq) → 2 Na⁺ (aq) + CO₃²⁻ (aq)
From the equation above, 1 mole of Na₂CO₃ produces 2 moles of Na⁺ ions.
Number of moles of Na₂CO₃ that will produce 0.650 moles of Na⁺ ions = 0.650/2 moles
Number of moles that will produce 0.650 moles of Na⁺ ions = 0.325 moles of Na₂CO₃ solution.
Volume of Na₂CO₃ solution required = moles of Na₂CO₃/molarityVolume of Na₂CO₃ solution required = 0.325/1.5
Volume of Na₂CO₃ solution required = 0.216 L
Volume of Na₂CO₃ solution required in mL = 216 mL
In conclusion, the volume of Na₂CO₃ solution required is obtained from the molarity and moles of Na₂CO₃.
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how many molecules are there in 4.00 moles of carbon
with step-by-step please and thank you
Answer: 2.409 x [tex]10^{23}[/tex]
Explanation:
To find molecules, we multiply the number of moles by Avogadro's number over one mole of the element (in this case it is carbon).
[tex]4.00 C moles (\frac{6.022 x 10^{23}moleculesC }{1 C moles} )[/tex] = 2.409 x 10^23
A graduated cylinder is filled to
10.10 mL with water. A small piece
of granite is placed into the
cylinder, displacing the water to a
volume of 19.45 mL. What is the
volume of the granite in ml?
volume = [?] mL
Round your answer to the hundredths place.
Volume (cm³)
Well here is my explanation: 9.35 is added. Which, equals 19.45, which means the 9.35 is the granite. Now to round it up.
My answer rounds up nearing 19.451. If I am wrong, feel free to shame me!
A small piece of granite is placed into the cylinder, displacing the water to a volume of 19.45 mL. The volume is 19.451.
What is volume?Volume is the three-dimensional area that a substance occupies or that is encircled by a surface. The cubic meter is the common unit of volume in the International System of Units (SI).
The liter (L) is the volume unit used in the metric system. A 10-centimeter cube has a volume equal to one liter. Gases have a volume equal to the internal capacity of the container since they fill their containers to the brim.
Containers with a designated volume or one whose internal shape is known are frequently used to measure liquids. Measuring cups, graded cylinders, flasks, and beakers are a few examples of the tools used to measure liquid volume.
Therefore, A small piece of granite is placed into the cylinder, displacing the water to a volume of 19.45 mL. The volume is 19.451.
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What is density?
A.The volume of an object.
B.The weight of an object.
C.The measure of mass of a material within a given space.
D.The mass of an object.
+11 points
Answer:
C.The measure of mass of a material within a given space.
Explanation:
C. The measure of mass of a material within a given space.
Consider yourself on that chair, are you a closed system, open system or isolated system? Give a reason for your answer!
Human body can be both closed and open system.
Human body is closed system in sense that all its constituents are closed within human body and it can be open system in sense that the entire system includes both human body and its interacting environment.
There is always temperature difference between the human body and the environment, the body absorb or emits heat.Open system can exchange energy and matter, example - water in an open beaker, human body Closed system can exchange only energy but not matter, example-boiling water in covered pan, air conditioner. -Isolated system can not exchange energy and matter, example-.thermos flaskLearn more about open and closed system _
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What has 4 legs up and down?
Answer:
A bed
Explanation:
Four legs up, four legs down, soft in the middle, and hard all round.
Liquid hexane (CH3(CH2)4CH3) reacts with gaseous oxygen gas (O2) to produce gaseous carbon dioxide (CO2) and gaseous water (H2O) . If 24.0g of carbon dioxide is produced from the reaction of 22.40g of hexane and 124.1g of oxygen gas, calculate the percent yield of carbon dioxide.
Round your answer to significant figures.
54% is the calculated percent yield.
The correct answer is:
Finding the limiting reactant is the first step. To do this, we figure out how many moles there are of each ingredient and divide the answer by the stoichiometric coefficient.
3.4 g octane divided by 114.23 g/mol yields 0.030 mol octane.
0.015 mol octane/2 0.030
5.9 g O2 / 32 g/mol equals 0.18 mol O2.
0.0074 mol = 0.18 mol O2/25
The limiting reactant in this example is oxygen, which is the lower number. The value is in accordance with the reaction's theoretical yield. In a similar manner, the product is used to determine the genuine yield. 0.0636 mol CO2 is equal to 2.80 g CO2/44.01 g/mol.
0.00398 mol = 0.0636 mol CO2/16
The ratio of the two times 100 is what determines the percent yield.
% yield = 0.0398/0.0074 * 100, or 54%.
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Which are reactions that release energy?
Which monatomic ions would you expect potassium (Z=19) and oxygen (Z=8) to form?
The monoatomic ion of potassium is K+ and Oxygen is O2-
The term "monatomic ion" refers to an ion with only one atom. A polyatomic ion is one that has more than one atom, even if they are all from the same element.The monatomic ions generated by potassium (K) and Oxygen (O) are being askedwe will first look for the group number that an element belongs to in order to establish the charge of that element. For non-metals, the charge of the ion is calculated by deducting 8 from the group number For metals, the charge of the ion is equal to the group number.Since K is a metal, its ion is a cation with a charge of 1, and it is a member of group 1A. K+ is hence the potassium's monoatomic ion.similarly oxygen is non metal therefore the monoatomic ion of oxygen is O2−.Learn more about monoatomic ions here:
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Calculate the mass of 12.044x10^23 atoms of calcium
Answer: 2g
Explanation: 12.044 * 10^23/6.022*10^23 * 1 = 2
1.) A substance has a pOH of 5.9. Calculate the [OH-] of the substance and explain how you reached your answer? (30 points) 2.) If the pH of a substance is 3, what is the pOH of the substance? Explain how you reached your answer. (35 points) 3.) Would you expect the [H3O+] concentration of hydrogen sulfide (H2S) to be high or low? Explain your answer. (35 points)
The pOH of the substance is known to be given by the hydroxide ions. A substance has a pOH of 5.9. The [OH-] of the substance is 7.23.
What is pOH?By estimating the concentration of OH ions in a solution, pOH can be used to gauge both acidic or alkaline a solution is. The OH ion concentration's negative logarithm is known as pOH.
pOH = -[tex]\rm -Log_{10}[OH]^{-}[/tex]
In this problem,[tex]\rm -Log_{10}[OH]^{-}[/tex]
pOH = ] = [tex]\rm -Log_{10}[OH]^{-}[/tex]
- log₁₀[5.9] = 7.23
A substance has a pOH of 5.9. The [OH-] of the substance is 7.23 .
Once you get the value of pOH we will get the value of pH.
pOH = 14 - pH
pH = 14 - 3 = 11
An acid that is weak is [tex]\rm H_{2} S[/tex]. As a result, has a pH of 3.92.
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Define chemical reaction with examples
Answer:
A chemical reaction is a process where bonds are formed between reactant elements causing interaction hence products are formed.
The two types of chemical reaction:
[tex]{ \boxed{ { \rm{ \bold{ \dashrightarrow \: reversible \: reaction}}}}}[/tex]
This is a reaction where reactants interact chemically to form respective products and also products can react to reverse the reaction (to form reactants).
An example of reaction of hydrogen and oxygen:
[tex]{ \rm{2H_{2(aq)} +O_{2(aq)} \: {}{ ^{ \dashrightarrow}_{ \dashleftarrow} \: 2H _{2}O _{(l)} }}}[/tex]
[tex]{ \boxed{ \rm{ \bold{ \dashrightarrow irreversible \: reaction}}}}[/tex]
It is a one way reaction, cannot be reversed
[tex]{ \rm{Mg_{(s)} + N _{2(g) \: }\rightarrow \: \: Mg _{3} N _{2(s)} }}[/tex]
please don't search this up thx or ill taker the points back- the question I need help is-What are respiratory disorders? Explain that term in your own words.
These are diseases that affect primarily the lungs or any other part of the respiratory system.
What are respiratory disorders?The term respiratory disorders refers to those diseases that affect primarily the lungs or any other part of the respiratory system. These are the diseases that prevent a person from breathing in and out normally and prevent the lungs from playing its usual role in gaseous exchange.
The respiratory disorders could be able to make a person not to be able to breathe well and it may lead to hospitalization and death of the patient of adequate treatment is not sought from an expert who could diagnose and treat such respiratory disorders.
The common types of respiratory disorders are;
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Rutherford used a beam of alpha particles for his scattering experiment what is the de Broglie wavelength of an alpha particle moving at a velocity of 2.15×10^7 m per second
The wavelength of an electron moving with a velocity of 2.05×10^7 ms^−1 is 3.55×10^−11 m.
What is de Broglie wavelength ?
In accordance with wave-particle duality, all quantum mechanical objects exhibit the De Broglie wavelength, which establishes the probability density of discovering the object at a specific location in the configuration space.
The de-Broglie equation can be used to determine an electron's wavelength.
λ= h/mv
= 6.626×10^−34 Js / 9.11×10 ^−31 kg×2.05×10^7 m/s
=3.55×10^−11 m
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Question:
Calculate the wavelength of an electron moving with a velocity of 2.05×10^7 ms^−1.
(d) Why did Thomson conclude that atoms also contain
a positive charge?
Answer: To counterbalance the negative charge on the electrons.
Explanation:
The plum pudding model
Thomson knew that atoms had an overall neutral charge. Therefore, he reasoned that there must be a source of positive charge within the atom
Thomson found that the path taken by the cathode ray could be bent towards a positive metal plate, and away from a negative metal plate. As a result, he reasoned that the particles in the cathode ray were negative.
: )
will mark u brainliest Question
What is the equation of the given line?
The equation of this straight line is equal to y = -1/2x + 1.
How to calculate the equation of the given line?First of all, we would determine the slope of the straight line by using this formula:
[tex]Slope,\;m = \frac{Change\;in\;y\;axis}{Change\;in\;x\;axis}\\\\Slope,\;m = \frac{y_2\;-\;y_1}{x_2\;-\;x_1}[/tex]
By critically observing the graph, the points on the x-axis and y-axis is given by:
Points (x₁, x₂) = (0, 2)
Points (y₁, y₂) = (1, 0)
Substituting the given points into the formula, we have;
Slope, m = (0 - 1)/(2 -0)
Slope, m = -1/2
In Mathematics, the y-intercept of any graph occurs at the point where the value of "x" is equal to zero (0).
y-intercept = (0, 1)
Mathematically, the standard form of the equation of a straight line is given by;
y = mx + c
Where:
x and y are the points.m is the slope.c is the intercept.Substituting the parameters into the formula, we have;
y = -1/2x + 1.
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