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Marysya12 [62]
3 years ago
9

Which of the following elements contains 7 valence electrons?

Chemistry
2 answers:
Evgesh-ka [11]3 years ago
7 0

Answer:

Halogens

Explanation:

Because elements can have 8 valence elctrons so noble gas group 18 has 8 valence electrons and previous group before group 18 or noble gas is called Halogens or group 17 whatever you want to prefer periodic table has all of informations

Liono4ka [1.6K]3 years ago
6 0

Answer:

Elements: F, Cl, Br, I, At

Explanation:

Hi there,

When you are trying to find the valence electrons for an element, look at the last number of the electron configuration.

For example, if you want to find the number of valence electrons of Carbon (C), you notice that the electron configuration is<u> 2 - 4.</u>

We know that this element has four valence electrons because the last number in its electron configuration is 4.

For your question, simply find all of the elements that have the number 7 as the last number on its electron configuration on the periodic table.

Hope this answer was helpful. Cheers.

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If 20 mL of gas is subjected to a temperature change from 10°C to 100°C and a pressure change from 1 atm to 10 atm,
Evgesh-ka [11]

Answer:

E. None of these

Explanation:

We know, By GAS laws,

PV = NRT, where p- pressure, v- volume, n- number of moles, R- gas constant ,and T- temperature

Now, In the question, the number of moles remains the same as the gas is the same. so n is constant so we can compare n before and after a temperature change.

\frac{P1V1}{RT1} = \frac{P2V2}{RT2}

where P1= 1 atm, P2 = 10 atm, V1= 20 mL, T1= 10°C and T2= 100°C

We don't have to worry about the standard units as they are present equally on both the sides and get cut, same goes for R( gas constant)

So putting values, we get

\frac{1*20}{R*10} = \frac{10*V2}{R*100}

Cutting, R on both sides and moving contents to the right so that only V2 is left on the left.

\frac{1*20*100}{10*10} = V2

∴ V2 = \frac{2000}{100}

∴ V2 = 20mL

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Which one of these are correct base pairs in DNA?
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What volume of water would be added to 16.5 ml of a 0.0813 m solution of sodium borate in order to get a 0.0200 m s?
raketka [301]
When diluting solutions from concentrated solutions the following formula can be used 
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the volume of the diluted solution prepared is 67.1 mL.
the volume of water that should be added to get a final volume of 67.1 mL is (67.1 - 16.5 ) = 50.6 mL
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Explanation:

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