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Katen [24]
2 years ago
6

Imagine a rock comprised entirely of an unstable isotope. After three half-lives, how much of the parent isotope remains

Chemistry
1 answer:
uysha [10]2 years ago
7 0

Answer:  After three half-lives 1/8 (12.5%) of the original sample remains

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The first excited electronic energy level of the helium atom is 3.13 x 10-18 J above the ground level. Estimate the temperature
salantis [7]

Answer:

75603.86473 K

Explanation:

Given that:

The 1st excited electronic energy level of He atom = 3.13 × 10⁻¹⁸  J

The objective of this question is to estimate the temperature at which the ratio of the population will be 5.0 between the first excited state to the ground state.

The formula for estimating the ratio of population in 1st excited state to the ground state can be computed as:

\dfrac{N_2}{N_1} = e ^{^{-\dfrac{(E_2-E_1)}{KT}}} =   e ^{^{-\dfrac{(\Delta E)}{KT}}}

From the above equation:

Δ E = energy difference =  3.13 × 10⁻¹⁸  J

k = Boltzmann constant = 1.38 × 10⁻²³  J/K

\dfrac{N_2}{N_1} = 0.5

Thus:

0.05 =e^{^{ -\dfrac{3.13 \times 10^{-18} \ J}{1.38\times 10^{-23 \ J/K}\times T}}}

In (0.05) = { -\dfrac{3.13 \times 10^{-18} \ J}{1.38\times 10^{-23 \ J/K}\times T}}}

-3.00 = { -\dfrac{3.13 \times 10^{-18} \ J}{1.38\times 10^{-23 \ J/K}\times T}}}

-3.00 = -226811.5942 \times \dfrac{1}{T}

T =  \dfrac{-226811.5942}{-3.00 }

T = 75603.86473 K

4 0
3 years ago
Hydrogen bonds form between molecules containing _________ bonds; the hydrogen bond is between a hydrogen atom of one molecule a
nasty-shy [4]

Answer:

The answer is A. Polar covalent; negatively

Explanation:

Hydrogen bonds form between molecules containing polar covalent bond the hydrogen bond is been a hydrogen atom of one molecule and a partially negative charged atom of another.

Example H_{2}O (water):- It contain a slight positive charge on one side and a slight negative charge on the other.

5 0
3 years ago
Which is the BEST example of refraction?
Fudgin [204]
C) A laser beam looks bent when it passes through glass blocks.

Hope this helps!
5 0
3 years ago
Read 2 more answers
When CaCl2 and Zn react together, zinc (Zn) can replace chlorine (Cl) in the compound because zinc is higher on the periodic tab
Phantasy [73]

Answer:

The answer to your question is: false

Explanation:

Zinc is a metal, Chlorine is a nonmetal, Zinc can replace another metal not a non metal.

3 0
3 years ago
Read 2 more answers
A 3.82-g sample of magnesium nitride is reacted with 7.73 g of water. mg3n2 (s) + 3 h2o (â) â 2 nh3 (g) + 3 mgo (s) the yield of
horrorfan [7]
The reaction is properly written as

Mg₃N₂ (s) + 3 H₂O (l) --> 2 NH₃<span> (g) + 3 MgO (s) 

Molar mass of Mg</span>₃N₂ = 100.95 g/mol
Molar mass of H₂O = 18 g/mol
Molar mass of MgO = 40.3 g/mol

Moles Mg₃N₂: 3.82/100.95 = 0.0378
Moles H₂O: 7.73/18 = 0.429 

Theo H₂O required for available Mg₃N₂: 0.0378*3/1 = 0.1134 mol
Hence, the limiting reactant is Mg₃N₂.
Thus,

Theoretical Yield = 0.0378 mol Mg₃N₂ * 3 mol MgO/Mg₃N₂ * 40.3 g/mol
Theo Yield = 4.57 g

Percent Yield = Actual Yield/Theo Yield * 100
Percent Yield = 3.60 g/4.57 g * 100 =<em> 78.77%</em>
5 0
3 years ago
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