Answer:
the first country that uses paper currency is china
the first use of paper currency can be traced back to the year 806 AD in China where they were used as flying currency
A chemist uses hot hydrogen gas to convert chromium(III) oxide to
pure chromium. How many grams of hydrogen are needed to
convert 76 grams of chromium(III) oxide, Cr203?
Answer: 3.024 g grams of hydrogen are needed to convert 76 grams of chromium(III) oxide, [tex]Cr_{2}O_{3}[/tex]
Explanation:
The reaction equation for given reaction is as follows.
[tex]Cr_{2}O_{3} + 3H_{2} \rightarrow 2Cr + 3H_{2}O[/tex]
Here, 1 mole of [tex]Cr_{2}O_{3}[/tex] reacts with 3 moles of [tex]H_{2}[/tex].
As mass of chromium (III) oxide is given as 76 g and molar mass of chromium (III) oxide [tex](Cr_{2}O_{3})[/tex] is 152 g/mol.
Number of moles is the mass of substance divided by its molar mass. So, moles of [tex]Cr_{2}O_{3}[/tex] is calculated as follows.
[tex]No. of moles = \frac{mass}{molar mass}\\= \frac{76 g}{152 g/mol}\\= 0.5 mol[/tex]
Now, moles of [tex]H_{2}[/tex].given by 0.5 mol of [tex]Cr_{2}O_{3}[/tex] is calculated as follows.
[tex]0.5 mol Cr_{2}O_{3} \times \frac{3 mol H_{2}}{1 mol Cr_{2}O_{3}}\\= 1.5 mol H_{2}[/tex]
As molar mass of [tex]H_{2}[/tex] is 2.016 g/mol. Therefore, mass of [tex]H_{2}[/tex] is calculated as follows.
[tex]No. of moles = \frac{mass}{molar mass}\\1.5 mol = \frac{mass}{2.016 g/mol}\\mass = 3.024 g[/tex]
Thus, we can conclude that 3.024 g grams of hydrogen are needed to convert 76 grams of chromium(III) oxide, [tex]Cr_{2}O_{3}[/tex].
HELPPP ASAP 10 POINTSS
Which feature of a sound wave directly affects the pitch of the sound? (Pitch is whether it is sounds low like a rumble of thunder or high like a bird chirping)
Question 3 options:
frequency
wavelength
amplitude
longitude
Answer:
wavelength
Explanation:
_H2+O2=_H2O
balance help please
what is the chemical formula for aluminium?
Answer
Aluminum is a silvery-white metal which is extremely soft by nature. Totally earth's crust contains 8% of Aluminum. Aluminium is a low-density nonmagnetic and ductile metal which can be made into sheets or wires as required
Explanation:
Answer:
Al
Explanation:
Aluminum is a silvery-white metal which is extremely soft by nature. Totally earth's crust contains 8% of Aluminum.
2.14g of sodium sulfide react with excess hydrochloric acid to form sodium chloride and dihydrogen sulfide.
BALANCE IT TO AN EQUATION
Answer:
2.14 Na2S + 1.99 HCl ----> 3.20 NaCl + 0.935 H2S
Explanation:
The Balanced equation is
Na2S + 2HCl = 2NaCl + H2S
As we can see -
78.0452 g/mol of sodium sulfide reacts with 2 mole of HCl.
Mass of one mole of HCl = 36.458 g/mol
So, 78.0452 g/mol of sodium sulfide reacts with 2* 36.458 g/mol of HCL to produce 2* 58.44 g of NaCl and 34.1 g/mol of H2S
Thus,
2.14g of sodium sulfide will react with (2* 36.458/78.0452)* 2.14 of HCl
2.14g of sodium sulfide will react with 1.99 g of HCl
2.14 Na2S + 1.99 HCl ----> (2* 58.44/78.0452) *2.14 NaCl + (34.1/78.0452) * 2.14 H2S
2.14 Na2S + 1.99 HCl ----> 3.20 NaCl + 0.935 H2S
What is an example of Chemical energy to thermal energy to electrical current?
Answer:
Coal is burned at power plant.
Explanation:
the chemical Energy is released as coal changes
have a good day
What is the momentum of a motorcycle and a rider weighing 215 kg traveling at a speed of 62 meters per second?
Answer:
[tex]p=13330kg*\frac{m}{2}[/tex]
Explanation:
Hello there!
In this case, since the momentum of any body is calculated by multiplying the mass and the velocity:
[tex]p=m*v[/tex]
We simply need to multiply the 215 kg of the motorcycle by the velocity it has, 62 m/s to obtain:
[tex]p=215kg*62m/s\\\\p=13330kg*\frac{m}{2}[/tex]
Regards!
What causes day and night?
Make sure you give a full, detailed answer, not just one sentence.
Answer:
The earth's rotation, earth is rotating, so one side of earth will be hit by the sun, and the other wont be hit, making it dark, but since earth rotates, it causes it to turn, making one side have daylight, and the other, darkness, which the light you see is from the sun's reflection on the moon
Hope this helps
What is the difference between strong and weak acids
Answer:
Weak acids don't fully dissociate in the solvent, whereas strong acid do.
Explanation:
Answer: Strong acids dissociate fully in water to produce the maximum number of H + ions. ... Weak acids, such as ethanoic acid (CH 3COOH), do not fully dissociate
Explanation:
Los ácidos fuertes se disocian completamente en agua para producir el máximo número de iones H +. ... Los ácidos débiles, como el ácido etanoico (CH 3COOH), no se disocian completamente
Which of these phrases accurately describe disproportionation? Check all that apply.
A single compound reacts with itself.
A single compound oxidizes and reduces a second compound.
A single compound is simultaneously oxidized and reduced.
A single compound is produced by the reaction of two ions.
A single compound acts as both the oxidizing agent and the reducing agent.
ANSWER: A,C,E on E2020
Answer:
A single compound is simultaneously oxidized and reduced.
Explanation:
In chemistry, disproportionation is a simultaneous oxidation and reduction of a single chemical specie.
What this means is that; in a disproportionation reaction, only one compound is both oxidized and reduced. This implies that two products are formed during disproportionation. One is the oxidized product while the other is the reduced product.
Consider the disproportionation of CuCl shown below;
2CuCl -----> CuCl2 + Cu
Here, CuCl2 is the oxidized product while Cu is the reduced product.
Answer:
A & c & e
Explanation:
Explain ocean floor spreading and how this process is related to the mid-ocean ridge
Answer:
Seafloor spreading is a process that occurs at mid-ocean ridges, where new oceanic crust is formed through volcanic activity and then gradually moves away from the ridge.
Explanation:
Mid-ocean ridges and seafloor spreading can also influence sea levels. As oceanic crust moves away from the shallow mid-ocean ridges, it cools and sinks as it becomes more dense. ... Seafloor spreading proves that the ocean itself is a site of tectonic activity.
Helium only has two valence electrons and is a stable atom. How is this possible when atoms
need 8 valence electron to become stable?
Answer:
Explanation:
Helium (He) is similar in that it, too, only has room for two electrons in its only valence shell. Hydrogen and helium have only one electron shell. The first shell has only one s orbital and no p orbital, so it holds only two electrons. Therefore, these elements are most stable when they have two electrons.
A sample of krypton occupies 15.0 L at a pressure of 2.1 atm. Use Boyle's Law to find the pressure of the krypton when the volume is decreased to 4L.
Answer:
7.5 atm
Explanation:
Given that,
Initial volume, V₁ = 15 L
Pressure, P₁ = 2.1 atm
Final volume, V₂ = 4L
We need to find the final pressure. The mathematical relation between volume and pressure is given by :
[tex]\dfrac{V_1}{V_2}=\dfrac{P_2}{P_1}\\\\P_2=\dfrac{V_1P_1}{V_2}\\\\P_2=\dfrac{15\times 2}{4}\\\\P_2=7.5\ atm[/tex]
So, the final pressure is equal to 7.5 atm.
What is 90 kPa when converted to atm?
A. 0.5 atm
B. 0.88 atm
C. 1 atm
D. 1.5 atm
Can you show the work
Why Uranium consider as non-renewable resource? Please I need it now and short answer with simple meaning!!
Rate in its natural state uranium -235 is a non renewable energy. although small quantities go a long way .For example the fission of one pound of uranium release more energy than burning three million pounds of coal.Nuclear fission reacts splits atoms to release the enriched uranium.
How much of a 100.0 gram sample of Gold-98 remains after 8.1 days if
its half-life= 2.7 days?
50.0 g
12.5 g
6.25 g
25.0 g
Answer:
If half-life is 2.7 days then 8.1 days is three half-lives. 12.5%, or 12.5g, of AU-198 would remain.
Explanation:
How many formula units (particles of AgNO3) are in 5.50
grams of AgNO3?
a 1.93 x 1022 molecules
b 8.67 x 1021 molecules
C 0.032 molecules
d 6.14 1022 molecules
e, 3.22 x 1022 molecules
Answer:
2.0 X 10²² molecules of AgNO₃Explanation:
Given 5.50 grams of AgNO₃, how many formula units of AgNO₃ are contained in the 5.50 grams of AgNO₃? (formula wt. of AgNO₃ = 169,87 g/mole).
Solution:
1st convert grams to moles => moles AgNO₃ = 5.50 g AgNO₃ / 169.841g AgNO₃ = 0.032377 mole AgNO₃ 2nd calculate number of particles in 0.032377 mole AgNO₃ . Number AgNO₃ molecules in 0.032377 mole AgNO₃ = 0.032377 mole AgNO₃ X 6.023 x 10²³ molecules of AgNO₃ /1.0 mole AgNO₃ = 1.95007 X 10²² molecules of AgNO₃ in 5.50 grams of AgNO₃. The appropriate form of the answer should contain 2 Sig,Figs. based on the data point having the least number of sig.figs. in the given data. This then is 5.50 grams of AgNO₃ which has 2 sig.figs. Therefore, the number of AgNO₃ molecules in 5.5 grams of AgNO₃ = 2.0 X 10²² molecules of AgNO₃. (Note: 1.95 rounds to 2.0).The number of molecules of silver nitrate in 5.5 grams has been [tex]1.93\;\times\;10^2^2[/tex]. Thus, option A is correct.
The formula unit has been given as the number of molecules of the compound. The number of molecules in a mole of compound has been given by the Avogadro law.
According to the Avogadro law, the number of molecules in a mole of sample has been equivalent to the Avogadro number, i.e. [tex]6.023\;\times\;10^2^3[/tex].
Computation for formula unit of Silver nitrateThe given mass of silver nitrate has been 5.50 grams.
The molar mass of silver nitrate has been 169.84 g/mol.
The moles of silver nitrate has been:
[tex]\rm Moles=\dfrac{Mass}{Molar\;mass} \\\\
Moles=\dfrac{5.5}{169.84}\;mol\\\\
Moles=0.032\;mol[/tex]
The moles of silver nitrate in the sample has been 0.032 mol.
The number of molecules of silver nitrate has been:
[tex]\rm 1\;mole=6.023\;\times\;10^2^3\;molecules\\ 0.032\;mol=0.032\;\times\;6.023\;\times\;10^2^3\;molecules\\ 0.032\;mol=1.93\;\times\;10^2^2\;molecules[/tex]
The number of molecules of silver nitrate in 5.5 grams has been [tex]1.93\;\times\;10^2^2[/tex]. Thus, option A is correct.
Learn more about formula unit, here:
https://brainly.com/question/19293051
In general, agitation causes the dissolving rate of most solutes to:
A- remain the same
B- increase
C- vary unpredictably
D-decrease
write a paragraph to explain how the transformation of water from one state of matter to another is important for the water cycle
In order for us to have water to drink, it first needs to go through a process called the water cycle. And in that water cycle there’s a process called evaporation. Evaporation is the process by which water changes from a liquid to a gas. In order for it to rain we need clouds and clouds are made of water. The water is heated causing water molecules to convert into gas, that gas then goes through a process called condensation creating clouds. At some point those clouds will be full of water, and all that water will then cause the cloud to release the water molecules causing rain.
The water cycle shows the continuous movement of water within the Earth and atmosphere. It is a complex system that includes many different processes.
Liquid water evaporates into water vapor, condenses to form clouds, and precipitates back to earth in the form of rain and snow.There are four main parts to the water cycle:
Evaporation, Convection, Precipitation and Collection.
Evaporation is when the sun heats up water in rivers or lakes or the ocean and turns it into vapor or steam.
The water vapor or steam leaves the river, lake or ocean and goes into the air.
Learn more:
brainly.com/question/25226746
Scientist introducing a gene to the DNA of these fish that cause the fish to glow an example of which application of biotechnology?
A. Artificial selection
B. Genetic Engineering
C. cloning
D. Artificial intelligence
Answer:
The correct answer is B
Explanation:
Genetic engineering is an example of which application of because the genes are changed to get the desired features in an organism.
What is genetic engineering?Genetic engineering is the process in which we alter the genetic makeup of an organism to produce desired characterictics in that organism.
So we can conclude that Genetic engineering is an example of which application of because the genes are changed to get the desired features in an organism.
Learn more about here Genetic engineering: https://brainly.com/question/2780091
Please, can anyone confirm that my answers are correct?
Will give brainiest to first correct answer! (No links pls)
PLZ HELP
How many electrons are in an ion of calcium (Ca2+)?
A. 2
B. 18
C. 0
D. 22
Which shows an isomer of the molecule below?
Answer: C
Explanation:
Don’t trust the other person it’s not A
*view photo for answer*
pay attention! the answer choices aren't always in the same order!
Describe the law of conservation of mass in your own words *DO IT IN YOUR OWN WORDS PLEASE*
Answer:
Chemical reactions and physical transformations do not create or destroy mass in an isolated system, according to the law of conservation of mass. The mass of the products in a chemical reaction must equal the mass of the reactants, according to the conservation of mass law. The law of conservation of mass can be used to solve for unknown masses, such as how much gas is consumed or produced during a reaction.
A dry, solid rock conducts electricity better than a long, meta wire.
True
False
Answer:
false
Explanation:
metal such as copper, silver, etc conducts heat and electricity. an object such as a rock, plastic, paper does NOT conduct heat.
How many moles of carbon are needed to react with 5.44moles of so2
Answer:
1.25 moles
Explanation:
hope that helps :)
ps. im learning about that in school rn too
51.86% of all the isotopes of an element have a mass of 106.82 amu and 48.14% have a mass of 109.03 amu.
What is the average mass of this element?
Answer:
Average Mass = 107.88 amu
Explanation:
We can calculate the average mass of an element by mutlpying the mass of its isotopes by their respective relative abundance and then making a total sum. Meaning that for this case:
Average Mass = 106.82 amu * 51.86/100 + 109.03 amu * 48.14/100Average Mass = 107.88 amuHow many total atoms are there in C6H12O6 + 6O2?
Explanation:
C - 6 atoms
H - 12 atoms
O - 6 atoms + 12 atoms
total number of stoms = 6 + 12 + 6 + 12 = 36
8.45 cm - 3.55 cm = ?
Answer:
4.9cm or 4.90cm
Explanation:
Use column method and align the numbers. Make sure you add the decimal point before you write the answer, otherwise the value would be wrong.
Answer:
4.90
Explanation:
8.45.
-3.55
minus those two and you'll get the sum!
How are the electron structures of carbon (C) and oxygen (O) similar? PLEASE HELP
Answer:
Carbon and oxygen are similar in a few ways. They are both elements, which are the fundamental building blocks of all matter. This means that they both have protons and electrons. They also both have neutrons