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finlep [7]
3 years ago
14

How many electrons does Helium need to have a full outer shell

Chemistry
2 answers:
lbvjy [14]3 years ago
8 0

Answer:

i dont no about this one

Explanation:

NikAS [45]3 years ago
5 0
Two electrons are needed.
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Anything in red is the question
laila [671]

Answer:

  • Question 19: the three are molecular compounds.
  • Question 20: CuSO₄.5H₂O

Explanation:

<em>Question 19.</em>

  • C₂H₄
  • HF
  • H₂O₂

All of them are the combination of two kinds of different atoms in fixed proportions.

  • C₂H₄: two carbon atoms per four hydrogen atoms
  • HF: one hydrogen atom per one fluorine atom
  • H₂O₂: two hydrogen atoms per two oxygent atoms

Thus, they all meet the definition of compund: a pure substance formed by  two or more different elements with a definite composition.

Molecular compounds are formed by covalent bonds and ionic compounds are formed by ionic bonds.

Two non-metal elements, like H-F, C - C, C - H, H-O, H - H, and O - O will share electrons forming covalent bonds to complete their valence shell. Thus, the three compounds are molecular and not ionic.

<em>Question 20. </em>Formula of copper(II) sulfate hydrate with 36.0% water.

Copper(II) sulfate is CuSO₄. Its molar mass is 159.609g/mol

Water is H₂O. Its molar mass is 18.015g/mol

Calling x the number of water molecules in the hydrate, the percentage of water is:

       \dfrac{18.015x}{18.015x+159.609}=36\%\\ \\ \\ \dfrac{18.015x}{18.015x+159.609}=0.36

From which we can solve for x:

      18.015x=6.4854x+57.45924\\ \\ 11.5296x=57.45924\\ \\ x\approx4.98\approx5

Thus, there are 5 molecules of water per each unit of CuSO₄, and the formula is:

  • CuSO₄.5H₂O
4 0
3 years ago
the amount of water on Earth is _______but the form and location of the water _______ as it moves through the hydrologic cycle
Lorico [155]

Hey there!

I can't be sure my answers are the exact words, but it should be something along the lines of...

The amount of water on Earth is constant, but the form and location of the water changes as it moves through the water cycle.

This means that Earth has always had the same amount of water within in, along with it being the same water the whole time. No new water was introduced to our planet. Some of our water is liquid, some is solid, and some is gas. Some is deep in the soil and some is high up in the atmosphere. Some is in rain and some is in snow.

I hope this helps!

6 0
3 years ago
An element is?
Sidana [21]

i think it’s D , not sure though

4 0
3 years ago
Read 2 more answers
How many sugar molecules are in 0.734 mol sugar, C6H12O6? Please explain
Dmitrij [34]
To answer this question, you need to know the Avogadro number. To find the amount of sugar molecule from mol unit you need to multiply it by the Avogadro number.
The calculation should be like this: <span>0.734 mol * 6.02*10^23 molecule/ mol= 4.41 * 10^23 molecule</span>
7 0
3 years ago
TRUE or FALSE<br> Nonpolar molecules only have nonpolar bonds.
Kitty [74]

Answer:

its false

Explanation:

srry if its wrong ;-;

4 0
2 years ago
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