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Pie
3 years ago
16

The model below shows an atom of an element. 10 light gray and 8 dark gray balls sit at the center with 2 concentric black rings

around them. The inner ring has 2 medium gray balls on it, and the outer ring has 6 medium gray balls on it. At bottom, a dark gray ball = +1, a light gray ball = 0, a medium gray ball = negative 1. What is the atomic number of this atom? A. 6 B. 8 C. 9 D. 16
Chemistry
2 answers:
MA_775_DIABLO [31]3 years ago
9 0

Answer:

The Atomic Number of the atom of an element whose model is given is "8" that is option no. 'C' in the question.

Explanation:

An Atom comprises of 3 basic structures that are Protons, Neutrons and Electrons. The central part is the Nucleus which contains protons and neutrons having positive charge and no charge respectively. The electrons are revolving around the nucleus in electronic shells having the negative charge.

<u><em>ATOMIC NUMBER: </em></u>

Atomic number is the number of protons present inside the nucleus of an atom and it determines the place of that particular atom in the <u>Periodic Table.</u>

In the model, given in the question, the nucleus contains 2 types of balls dark gray colored and light gray colored. The key at the bottom shows the dark gray colored ball as having a positive charge and thus it represents the atomic number for the given atom of element which is <u><em>EIGHT (8).</em></u>

So, the atomic number for the given atom is 8 which is element OXYGEN.  

Juliette [100K]3 years ago
6 0

Answer:

8

Explanation:

i just counted the protons which is the same number as the electrons .___.

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Answer:

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3 years ago
The vapor pressure of water at 25.0°c is 23.8 torr. determine the mass of glucose (molar mass = 180 g/mol) needed to add to 500.
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P(solu) = n Pv(water)
when we have Pv(solu) = 22.8 and Pv(water) = 23.8 so by substitution:
22.8 = n * 23.8
n= 0.958
- we need to get the moles of glucose:
moles of water = 500 g(mass weight) / 18 (molar weight)= 27.7 mol
n = moles of water / ( moles of water + moles of glucose)
0.958   = 27.7 / ( 27.7+ moles of glucose)
0.958 moles of glucose + 26.5 = 27.7
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here we also need to get n (mole fraction of water )by using this formula:
Pv(solu) = n Pv(water)
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- total moles in solution = moles of water / moles fraction of water 
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∴ the molar mass of the solute = mass weight of solute / no.of moles of solute
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moles of urea (NH2)2 CO = mass weight / molar mass
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Pv(solu) = n P°v
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