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dezoksy [38]
3 years ago
15

Which one is a chemical reaction? Why?

Chemistry
1 answer:
Alex17521 [72]3 years ago
3 0

Answer:

Copper turns green on exposure to air

Explanation:

Liquid water freezes to form ice: Physical change

Reason: Water can melt back when it becomes ice.

Copper turns green on exposure to air: Chemical change

Reason: The copper can not change back from the green state when it turns green.

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Type the correct answer in the box.
Ivan

Answer:The answer is 3.33%. Anna reduced her CO2 emissions by 3.33% from using 600 gallons of gas annually than from using 900 gallons of gasoline annually.

Explanation:

5 0
3 years ago
What two nuclei are fused in the main fusion reaction of the sun? A. helium and helium B. helium and thorium C. hydrogen and hel
butalik [34]
C. hydrogen and helium
8 0
3 years ago
Read 2 more answers
Which of the following happens when an ionic bond is formed? (1 point)
bazaltina [42]

This problem is asking for an explanation of what happens when an ionic bond is formed. Although the choices are not given in the question, one can find them on the attached file and realize the answer is C "a less electronegative atom donates an electron to a more electronegative atom" according to:

<h3>Types of bonds:</h3><h3 />

In chemistry, the forces that hold atoms together are known as chemical bonds and act like connections for atoms to form compounds. There exist ionic and covalent bonds, so the formers occur when electrons are thoroughly donated from the least electronegative atom to the most electronegative one.

On the flip side, covalent bonds occur when the electrons are shared between the two or more of the atoms forming the compound. In such a way, one can discard choices A and B because they are more related to covalent bonds.

Therefore, one can select C "a less electronegative atom donates an electron to a more electronegative atom" as the correct answer, because not all the elements are able to donate more than one single electron, and the less its valency, the more ionic the compound turns out to be.

Learn more about types of bonds: brainly.com/question/792566

3 0
3 years ago
What is the energy of a single photon of blue light with a wavelength of 488 nm (488 × 10-9 m)?
Vinvika [58]
E = hf

c = speed of electromagnetic wave, c ≈ 3 * 10⁸ m/s, 
Planck's constant h = 6.63 *10⁻³⁴ Js

h = Planck's constnat,  Frquency, f = c/λ = (3*10⁸)/(488*10⁻⁹)

E = hf

E = hc/λ

E = (6.63 * 10⁻³⁴ * 3 * 10⁸) /(488 * 10⁻⁹)

Energy, E ≈ 4.0758 * 10⁻¹⁹  Joules.
3 0
3 years ago
Read 2 more answers
Fe2O3(s) + 3CO(g) ---&gt; 2Fe(l) + 3CO2(g) Steve inserts 450. g of iron(III) oxide and 260. g of carbon monoxide into the blast
baherus [9]

Answer: Theoretical yield is 313.6 g and the percent yield is, 91.8%

Explanation:

To calculate the moles :

\text{Moles of solute}=\frac{\text{given mass}}{\text{Molar Mass}}    

\text{Moles of} Fe_2O_3=\frac{450}{160}=2.8moles

\text{Moles of} CO=\frac{260}{28}=9.3moles

Fe_2O_3(s)+3CO(g)\rightarrow 2Fe(l)+3CO_2(g)

According to stoichiometry :

1 mole of Fe_2O_3 require 3 moles of CO

Thus 2.8 moles of Fe_2O_3 will require=\frac{3}{1}\times 2.8=8.4moles  of CO

Thus Fe_2O_3 is the limiting reagent as it limits the formation of product and CO is the excess reagent.

As 1 mole of Fe_2O_3 give = 2 moles of Fe

Thus 2.8 moles of Fe_2O_3 give =\frac{2}{1}\times 2.8=5.6moles of Fe

Mass of Fe=moles\times {\text {Molar mass}}=2.6moles\times 56g/mol=313.6g

Theoretical yield of liquid iron = 313.6 g

Experimental yield = 288 g

Now we have to calculate the percent yield

\%\text{ yield}=\frac{\text{Actual yield }}{\text{Theoretical yield}}\times 100=\frac{288g}{313.6g}\times 100=91.8\%

Therefore, the percent yield is, 91.8%

6 0
3 years ago
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