Explanation:
A physical change is one which can be reversed.it also does not produce any new substance.
changes in state such as the melting of a solid, the freezing and vaporization of a liquid as well as changes In shape are examples of physical changes
What did people use for energy before fossil fuel and electrical power energy was harnessed?
They used whale oil and steam power to run machines.
Humans had only their own muscles and a knowledge of levers and pulleys for power.
Humans burned wood to power their machines.
Humans used muscle power and direct wind and water power.
Before the occurance of Fossil fuel, our energy needs were modest. For heat, we relied on the sun—and burned wood, straw, and dried dung For transportation, the muscle of horses and the power of the wind in our sails took us to every corner of the world.
What is Fossil Fuel ?Fossil fuels are made from decomposing plants and animals.
These fuels are found in the Earth's crust and contain carbon and hydrogen, which can be burned for energy.
Coal, oil, and natural gas are examples of fossil fuels.
Hence, Before the occurance of Fossil fuel, our energy needs were modest. For heat, we relied on the sun—and burned wood, straw, and dried dung For transportation, the muscle of horses and the power of the wind in our sails took us to every corner of the world.
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Answer:
B is the answer.
Explanation:
sry if wrong :D
What is the noble gas configuration for tellurium (Te)?
The Periodic Table
OA. [Kr] 5s²4d105p4
O B. [Kr] 5s25p65d8
O C. [Xe] 5s25065
O D. [Xe] 5s24d1¹05p4
The correct answer to this question is option A.
The sentences below are things people might say if they were planning to invest or not planning to invest Sort them into the correct categories . am thinking about buying stocks Planning to Invest Not Planning to Invest don't know much about investing can't afford to buy stocks don't really like to take risks need a way to manage my money want to save money for my future
Investing :
"I'm considering investing in equities."
"I need a system for handling my finances."
"I need to put money away for the future."
No Investment :
"My knowledge of investment is limited."
"I am unable to purchase stocks."
"I don't particularly enjoy taking chances."
Explanation:
These are accurate because I recently completed the course that taught me these things.
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Why is aluminum considered a nonrenewable resource?
There are 4.9875 mol C, 7.9802 mol H,
and 2.00 mol O in the sample.
Divide each by the smallest number of
moles. What is the ratio for the C?
[?] C [ ]H[ ]0
Answer:
So, in 1 mol there are 6.02x10^23 atoms, regardless of the susbtance, only the weight of the mol changes. Doing a simple rule of 3 we can get many of the answers to your questions.
Explanation:
1mol of Ar → 6.02x10^23 atoms
0.25 mol → X
So now what we do is (0.25mol * 6.02x10^23 atoms)/1 mol = X
That gives us 1.505x10^23 atoms in 0.25 mol of Ar.
For this I'm guessing you mean the stable form of oxygen, O2. The Avogadro constant stays well, constant.
1 mol of O2 → 6.02x10^23 molecules
1.0×10^-4 mol of O2 → X molecules
So you can do (1.0×10^-4 * 6.02x10^23) / 1mol = X
(I feel like this is homework, so i will help you, but not give you all the answer, will be good practice to try yourself) :)
For this you need to know the weight of a mol of Be. Luckily the periodic table gives us that number. The number under each element is the weight in grams of 1 mol .
Answer:
C- 2.48925 H- 3.9901 O- 1
Explanation:
Read the instructions
What are the environmental impacts of chemical industries using distillation to separate chemical solutions?
Answer:
The production process often produces offensive odours and may also create by-products that can contaminate air and ground water. Many industrial separation processes have requirements and consequences that influence where they are located.
Explanation:
hope it's helpful to you
●
As a solution becomes more basic or alkaline, how does it affect the concentration of
H3O* and OH ions?
What is the volume in L of a 0.825 mole sample of Ar at 600 mm Hg and 300 K? Report your answer to the nearest tenth of a L. (Moodle is looking for a number only, no units.)
The volume is 2.608L
Given the value of n is 0.825 mole , pressure is 600mm = 0.789bar and Temperature = 300K
We need to calculate the volume in L
As we know the values of number of moles , pressure and Temperature is given
So , to calculate the volume we will use the ideal gas law
The equation of state for a fictitious perfect gas is known as the ideal gas law, sometimes known as the generic gas equation. Although it has several restrictions, it is a decent approximation of the behavior of numerous gases under various circumstances.
Ideal gas law formula
PV = nRT
0.789*V = 0.825*8.3143*300
V = 0.825*8.314*300/0.789
V = 2.608*10^3
V = 2.608 L
Hence the Volume is 2.608 L
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What is a spring tide? When and why does it occur?
A spring tide occurs when there is a new or full moon in the solar system.
What is Spring tide?This is the type of tide which occurs when the sun, moon and earth are in line and occurs between three to four times per year.
Lunar and solar tides also line up and reinforce each other to produce this type of tide.
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What is the optimum pH of formic acid-formate buffer? (The pK, of formic acid is 3.75.)
1.875
3.75
5.625
7.50
The optimum pH of formic acid - formate buffer is 3.75
What is Buffer ?
A substance or a solution which resists any changes in pH, when acid or alkali is added to it.
pH = pKa + log[base] / [acid]
Considering equimolar concentration of acid and base
pH = 3.75 + log(x)/(x)
pH = 3.75 + log (1)
pH = 3.75 + 0
pH = 3.75
Hence,
The optimum pH of formic acid - formate buffer is 3.75
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which experimental technique was most likely used by the students to determine the rate of reaction?
The students can determine the rate of reaction by measuring change in concentration of reactant or product with time.
What is rate of reaction?The rate of a reaction is the rate at which reactant molecules are used up or the rate at which product molecules are formed.
The rate of a reaction can be determined by measuring the change in concentration of the reactant at each given time in a reaction.
The rate of reaction can be also be determined by measuring the change in concentration of the product at each given time in a reaction.
Therefore, the students can determine the rate of reaction by measuring change in concentration of reactant or product with time.
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7 on the pH scale represents what?
Answer:
seven on the ph scale is the neutral point
Explanation:
The range goes from 0 - 14, with 7 being neutral. pHs of less than 7 indicate acidity, whereas a pH of greater than 7 indicates a base. pH is really a measure of the relative amount of free hydrogen and hydroxyl ions in the water.
some one please help me
Answer:
measure their densities
Which are correct statements about the emission spectrum of hydrogen in the visible region
The statement that is correct about the emission spectrum of hydrogen in the visible region is that the line corresponding to the greatest emission of energy is in the ultraviolet region.
What is hydrogen spectrum?Hydrogen spectrum is defined as the dissociation of hydrogen atom upon action of electric current into spectral lines that can be seen in that visible light.
These lines falls under the electromagnetic wave of ultraviolet and infrared regions. But the lines of greatest emission is found in the ultraviolet region.
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How many grams of methane,
CH4, are produced from the
complete reaction of 5.15 moles
of carbon monoxide, CO?
CO+ 3H₂ → H₂O + CH4
[? ] g CH4
Answer:
82.606g
Explanation:
[tex]5.15mol CO* \frac{1 mol CO}{1 mol CH4} *\frac{16.04 g CH4}{1 mol CH4} =82.606g CH4[/tex]
The liquids having same boiling point cannot be seperated from its mixture by distillation, why?
Answer:
Explanation:
They cannot be separated by distillation since it depends on a liquid's ability to boil at a certain temperature. If you have two liquids with the same boiling temperatures, the proportion of each in the vapor phase will be about equal, making it impossible to separate them. Although they presumably do not have the same freezing point, you might use a different method like chromatography or work with their freezing points instead. You could then selectively crystallize one component while leaving the other as a pure liquid.
____________
Definitions:
Distillation:
#1: The volatilization or evaporation and subsequent condensation of a liquid, as when water is boiled in a retort and then the steam is condensed in a cool receiver.
Answer:
Because different compounds often have different boiling points, the components often separate from a mixture when the mixture is distilled. The boiling point is the temperature at which the vapor pressure of the liquid phase of a compound equals the external pressure acting on the surface of the liquid.
Explanation:
Which are the two major greenhouse gases?
OA. CO₂ and CH4
OB. 0₂ and H₂0
OC. CH₂0 and CO
OD. NO and NO₂2
Answer:
A. CO2 and CH4
The two major greenhouse gases are CO₂ and CH₄ and the correct option is option A.
What are Greenhouse Gases?Greenhouse gases are gases in Earth’s atmosphere that trap heat. They let sunlight pass through the atmosphere, but they prevent the heat that the sunlight brings from leaving the atmosphere.
These gases have the property of absorbing infrared radiation (net heat energy) emitted from Earth’s surface and reradiating it back to Earth’s surface, thus contributing to the greenhouse effect.
Each of these gases can remain in the atmosphere for different amounts of time, ranging from a few years to thousands of years.
Examples of greenhouse gases are carbon dioxide, methane and water vapour.
Therefore, the two major greenhouse gases are CO₂ and CH₄ and the correct option is option A.
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how power station that produce electricity affect our environment what can we do to minimize these harmful effects?
Answer:
they help becuz they dont use any extra power and the are reneable
How many grams of nitrogen,
N2, would be required to create 9.3
moles ammonia, NH3?
Answer:
Explanation:
Hi there!
N₂+3H₂⇋2NH₃
The molecular mass of NH₃ is 34
The mass of N₂ is 28 and mass of H₂ is 2.
Then,
2 moles of NH₃ is created by 28 g of N₂
1 moles of NH₃ is created by 28/2 g of N₂
9.3g of NH₃ is created by (28/2)*9.3 moles of N₂
Therefore, 130.2 g of N₂ is required to create 9.3 moles of NH₃.
Hope it helps!
N₂+3H₂⇔2NH₃
moles N₂ = 1/2 x 9.3 = 4.65
mass N₂ = 4.65 x 28 g/mol = 130.2 g
Calculate the bond length (in picometers) of a chemical bond between bromine and sulfur.
Bromine—atomic radius: 119 pm; covalent radius: 114 pm; ionic radius: 182 pm.
Sulfur—atomic radius: 109 pm; covalent radius: 102 pm; ionic radius: 184 pm.
The bond length of a chemical bond between bromine and sulfur is 216 picometers.
Explanation:Bromine and sulfur reacts with each other to form Sulfur dibromide.Sulfur dibromide is a covalent compound which means that a chemical bond exist between them is covalent bond.So, for finding a bond length of a covalently bonded compound we need to add the covalent radiuses of the two atoms.Given,
Covalent radius of bromine is 114 pm;
and covalent radius of sulfur is102 pm.
∴ Bond length of the sulfur dibromide= Covalent radius of bromine + covalent radius of sulfur
∴ Bond length = 114 + 102
∴ Bond length = 216 pm.
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The energy produced by the snack in an experiment is calculated to be 41,800 J/g. What is the energy of the snack in Calories/
gram?
snack energy = [?] Cal/g or kcal/g
remember there are 4.18J per 1 calorie
The energy of the snack in calories per gram is 9983.3 Calories/gram.
What is the energy of a snack?The energy that is contained in a snack is obtained from a calorimeter when the snack is burnt in a calorimeter. The mass of the snack that is burnt is measured in terms of energy output of the calorimeter.
If 1 calorie = 4.18J
x calorie = 41,800 J
x = 41,800 J * 1 calorie/4.18J
x = 9983.3 Calories/gram
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The products of __________ combustion are carbon monoxide, carbon and water. what one word completes this sentence?
Answer:
Complete combustion
Explanation:
To solve such this we must know the concept of combustion reaction. Therefore the products of complete combustion are carbon monoxide, carbon and water.
What is chemical reaction?Chemical reaction is a process in which two or more than two molecules collide in right orientation and energy to form a new chemical compound. The mass of the overall reaction should be conserved.
There are so many types of chemical reaction reaction like combustion reaction, acid base reaction, double displacement reaction, combustion reactions. The products of complete combustion are carbon monoxide, carbon and water. Large amount of heat is also released in combustion reaction
Therefore the products of complete combustion are carbon monoxide, carbon and water.
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A sample of carbon dioxide gas occupies a volume of 250 mL at 25c what volume will it occupy at 95c
Considering the Charles's law, the sample of carbon dioxide gas will occupy 308.72 mL.
Charles's lawCharles's law establishes the relationship between the temperature and the volume of a gas when the pressure is constant. This law says that the volume is directly proportional to the temperature of the gas: for a given sum of gas at constant pressure, as the temperature increases, the volume of the gas increases and as the temperature decreases, the volume of the gas decreases.
Mathematically, Charles's law states that the ratio between volume and temperature will always have the same value:
[tex]\frac{V}{T} =k[/tex]
Considering an initial state 1 and a final state 2, it is fulfilled:
[tex]\frac{V1}{T1} =\frac{V2}{T2}[/tex]
Final volume in this caseIn this case, you know:
V1= 250 mLT1= 25 C= 298 K (being 0 C=273 K)V2= ?T2= 95 C= 368 KReplacing in Charles's law:
[tex]\frac{250 mL}{298 K} =\frac{V2}{368 K}[/tex]
Solving:
[tex]V2=368 K\frac{250 mL}{298 K}[/tex]
V2= 308.72 mL
Finally, the sample of carbon dioxide gas will occupy 308.72 mL.
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Answer:
310mL
Explanation:
A sample of carbon dioxide gas occupies a volume of 250 mL at 25°C. What volume will it occupy at 95°C?
Use the formula:
V1
T1
=
V2
T2
Temperature conversion: __°C + 273 K
As you know, liquid hydrazine (N2H4) can be used as a rocket fuel. A rocket you designed has a total of 1.35E5 g of hydrazine when it loses power just beyond the atmosphere of Earth. It is on the dark side of the Earth at the time, and the external temperature is 116 K. By the time you notice, the internal temperature of the rocket (and the rocket fuel) has also reached 116 K. How much heat must be applied (in J) to the fuel to warm it back to its operating temperature of 298 K
The heat required to warm the fuel back to it's operating temperature is 3.83×10⁷ J
Data obtained from the question Mass (M) = 1.35×10⁵ g = 1.35×10⁵ / 1000 = 135 KgInitial temperature (T₁) = 116 KFinal temperature (T₂) = 298 KSpecific heat capacity (C) = 1559.45 J/KgK Heat (Q) =?How to determine the heat requiredThe heat required to warm the fuel can be obtained as follow:
Q = MC(T₂ – T₁)
Q = 135 × 1559.45 × (298 – 116)
Q = 135 × 1559.45 × 182
Q = 3.83×10⁷ J
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what's the geometry of sp³ hybridization ~
Answer:
For sp3 hybridized central atoms the only possible molecular geometry is tetrahedral.
There are 6.02 x 10^23 formula units Na2O in a sample. How many grams of Na2O is this? The molar mass of Na2O is about 62 g/mol.
Answer:
= 62g
Explanation:
We have been asked to find the mass of Na2O having 6.02 x 10^23 units.
We know that one mole of a substance contains 6.02 x10^23 units/particles.
That means we have one mole of Na2O.
To find the mass of Na2O we use the formula,
mass = number of moles x formula mass
= 1 mole x 62g/mol
= 62g
Therefore the mass of Na2O with 6.02 x 10^23 units is 62g.
When 4 mol of glucose is fermented, a mass of 55.2 g of ethanol is produced. Show that the percentage yield of ethanol is 15%
(Mr of C2H5OH = 45)
Theoretical yield =0.15 g
% yield = 15%
reaction
C6H12O6 → 2C2H5OH + 2CO2
from above reaction, we get to know that,
1 mole of glucose → 2 mole ethanol
for 4 mole of glucose → 8 mole of ethanol
\frac{55.2}{8(46)} = yield of ethanol
yield of ethanol = 0.15g
% yield = (experimental/theoretical )*100
% yield of ethanol = 0.15 x 100 =15%
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Which of the following reactions depicts a decompostion reaction?
Answer:
B it is decomposition reaction
Explanation:
In decomposition reaction compound is broken into two or other elements
How many moles of fluorine atoms are in a sample of fluorine that contains 7.45 x 10^24 fluorine atoms? (Report your answer to one place past the decimal point.
Based on the calculations, the number of moles of fluorine atoms present is equal to 12.4 moles.
How to calculate the moles of fluorine atoms?In order to determine the number of moles of fluorine atoms, we would calculate the number of atoms in 1 mole of an fluorine atoms in accordance with Avogadro's constant.
1 mole of fluorine atom = 6.02 × 10²³ molecules
X moles of fluorine atom = 7.45 × 10²⁴ molecules
Cross-multiplying, we have:
X = 7.45 × 10²⁴/6.02 × 10²³
X = 12.4 moles.
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pls help
1.
when a magnet spins within a coil of wires, what is produced?
-blue sparks
-glowing light
-nuclear energy
-an electric current
2.
when an electric current flows through a wire:
-a gravitational field is created around the wire
-the wire becomes very cold
-the wire begins to spin
-a magnetic field is created around the wire
help pls
Answer:
1d and 2d is the answer. Hope it helps