Answer: The correct answer is the option: B. An element with eight valence electrons is chemically unstable.
Explanation:
Hello! Let's solve this!
We will analyze each of the options:
A. The group number of the element provides a clue to the number of valence electrons: it is correct, since it provides the number of valence electrons.
B. An element with eight valence electrons is chemically unstable: this is not correct, since elements with eight electrons in the valence shell cannot react because they already have the last complete shell. Therefore, they are chemically stable.
C. The points must be placed one at a time on each side of the chemical symbol: it is correct, because that is the way to make the point diagram.
D. An atom is chemically stable if all the points are paired: this is correct since this verifies that the point diagram has been done well.
We conclude that the correct answer is the option: B. An element with eight valence electrons is chemically unstable.
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The mass of plutonium that will remain after 1000 years if the initial amount is 5 g when the half life of plutonium-239 (239pu, pu-239) is 24,100 years is 2.5 g
The equation is Mr=Mi(1/2)^n
where n is the number of half-lives
Mr is the mass remaining after n half lives
Mi is the initial mass of the sample
To find n, the number of half-lives, divide the total time 1000 by the time of the half-life(24,100)
n=1000/24100=0.0414
So Mr=5x(1/2)^1=2.5 g
The mass remaining is 2.5 g
- The half life is the time in which the concentration of a substance decreases to half of the initial value.
Learn more about half life at:
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2.91 mol Al * ( 26.982 g Al / 1 mol Al) = 78.518 grams
Answer:
The partial pressure of oxygen in the mixture is 296 mmHg.
Explanation:
The pressure exerted by a particular gas in a mixture is known as its partial pressure. So, Dalton's law states that the total pressure of a gas mixture is equal to the sum of the pressures that each gas would exert if it were alone.
This relationship is due to the assumption that there are no attractive forces between the gases.
So, in this case, the total pressure is:
PT=Phelium + Pnitrogen + Poxygen
You know:
- PT= 756 mmHg
- Phelium= 122 mmHg
- Pnitrogen= 338 mmHg
- Poxygen= ?
Replacing:
756 mmHg= 122 mmHg + 338 mmHg + Poxygen
Solving:
756 mmHg - 122 mmHg - 338 mmHg = Poxygen
Poxygen= 296 mmHg
<u><em>The partial pressure of oxygen in the mixture is 296 mmHg.</em></u>
Answer:
12:7
Explanation:
To Determine: To calculate the formula of the unknown binary compound of oxygen and nitrogen and to ratio in the next compound of the series using given data.Answer:The formula of the unknown compound .The ratio for atoms of oxygen to nitrogen inis .The mass ratio of oxygen to nitrogen in next member of the series of compounds is .Explanation:The mass ratio of toinis .The mass ratio of toin theunknown compound is .The atomic mass of the oxygen is .The atomic mass of the nitrogen is .The mass ratio of to in a molecule can be represented as: …… (1)Here,is the number of atoms of the oxygen in the molecule.is the mass of an atom of oxygen.is the number of atoms of the nitrogen in the molecule.is the mass of an atom of nitrogen.For unknown compound, substitutefor , for and for mass ratio in equation (1).The ratio of atoms of oxygen to nitrogen is , therefore, the expected formulas of the unknown compound is and . If the unknown compound is in a series with then the formula of the unknown compound and the formula for the next member of the series is .The ratio for atoms of oxygen to nitrogen inis .For , substitute 5 for , for , 2 for and for in equation (1).The mass ratio of oxygen to nitrogen in next member of the series of the compounds is .
