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2 years ago

The total number of the elements above with 2 valence electron is ____.

Chemistry

1 answer:

OverLord2011 [107]2 years ago

4 0

Answer:

four elements

Explanation:

He = 1s²

Be = 1s² 2s²

C = 1s² 2s² 2p²

Mg = 1s² 2s² 2p⁶ 3s²

Si = 1s² 2s² 2p⁶ 3s² 3p²

Ca = 1s² 2s² 2p⁶ 3s² 3p⁶ 4s²

Valence electrons are those electrons which are present in outer most electronic shell.

He, Be, Mg, Ca these four elements have 2 valence electrons.

While Si and C have four valance electrons.

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Which of the following processes have a ΔS < 0? Which of the following processes have a ΔS < 0? carbon dioxide(g) → carbon

Umnica [9.8K]

Answer:

All of the above processes have a ΔS < 0.

Explanation:

ΔS represents change in entropy of a system. Entropy refers to the degree of disorderliness of a system.

The question requests us to identify the process that has a negative change of entropy.

carbon dioxide(g) → carbon dioxide(s)

There is a change in state from gas to solid. Solid particles are more ordered than gas particles so this is a negative change in entropy.

water freezes

There is a change in state from liquid to solid. Solid particles are more ordered than liquid particles so this is a negative change in entropy.

propanol (g, at 555 K) → propanol (g, at 400 K)

Temperature is directly proportional to entropy, this means higher temperature leads t higher entropy.

This reaction highlights a drop in temperature which means a negative change in entropy.

methyl alcohol condenses

Condensation is the change in state from gas to liquid. Liquid particles are more ordered than gas particles so this is a negative change in entropy.

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3 years ago

Find the volumetric (mL/s) and mass (g/s) flow rates in an artery whose diameter is 0.3 mm and blood flow rate is 25 mm/s.

Setler [38]

I don’t know kid I don’t know ‍♂️

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2 years ago

By the reaction of carbon & oxygen , a mixture of CO &CO2 is obtained. What is the composition by mass of the mixture ob

Hatshy [7]

M(O₂)=20g
M(O₂)=32.0 g/mol
n(O₂)=20/32.0=0.625 mol

m(C)=12 g
M(C)=12.0 g/mol
n(C)=12/12.0=1.0 mol

2C + O₂ → 2CO
1 mol 0.625 mol 1 mol
0.625-0.5=0.125 mol

2CO + O₂ → 2CO₂
0.250 mol 0.125 mol 0.250 mol

n(CO)=1 mol - 0.250 mol = 0.750 mol
M(CO)=28.0 g/mol
m(CO)=0.750*28.0=21.0 g

n(CO₂)=0.250 mol
M(CO₂)=44.0 g/mol
m(CO₂)=0.250*44.0=11.0 g

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3 years ago

Are insert gases used in fluorescent

aksik [14]

Hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), sulfur hexafluoride (SF6) and nitrogen trifluoride (NF3).

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3 years ago

While setting up a beaker to boil a solution on a hot plate, you notice that the stirring is erratic and unstable. What should y

Crank

Given what we know, we can confirm that if while setting up a beaker you notice that the stirring is erratic and unstable, you should immediately turn off the stirring mechanism.

<h3>Why turn off the stirring mechanism?</h3>

The beaker is boiling a substance, making it very dangerous.
Unstable and erratic stirring can cause spilling or even a broken beaker.
The best course of action is to disable the stirring until the problem is fixed.
This will ensure the safety of everyone involved.

Therefore, we can confirm that in order to ensure the safety of all participants, if while setting up a beaker you notice that the stirring is erratic and unstable, you should immediately turn off the stirring mechanism.

To learn more about lab safety visit:

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2 years ago