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galina1969 [7]
3 years ago
7

Americium-241 is a radioactive substance used in smoke detectors. The half life of americium is 432 years. If a smoke detector i

nitially contains 1 gram of Americium 241, how much will remain in 432 years? A) 0.5g B) 1.0g C) 1.5g D) 2.0g
Chemistry
1 answer:
aksik [14]3 years ago
7 0
<span>The half life of americium is 432 years. That means that after 432 years only half(1/2) of initial amount will be left.
If we had 1 g, then after 432 years we will have only half of it.
1g*1/2=1/2 g=0.5 g
Answer is </span><span>A) 0.5g</span>
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An element has two naturally occurring isotopes, X-85 with a mass of 84.9118 amu and a natural abundance of 72.17%, and X-87 wit
QveST [7]

Answer:

This element is Rubidium (Rb) and has an average atomic mass of 85.468 u

Explanation:

The average mass of an element is calculated by taking the average of the atomic masses of its stable isotopes.

The enitre atomic mass = 100 % or 1

⇒ this consists of X-85 with 72.17 % abundance  with atomic massof  84.9118 g/mol

72.17 % = 0.7217

⇒ this consists of X-87 with  27.83 % abundance with atomic mass of 86.9092 g/mol

27.83 % = 0.2783

To calculate the mass of this isotope we use the following:

0.7271 * 84.9118 + 0.2783 * 86.9092 =85.468 g/mol

This element is Rubidium(Rb) and has an average atomic mass of 85.468 u

5 0
3 years ago
What mass of H2 is needed to react with 8.75 g of O2 according to the following equation: O2(g) + H2(g) → H2O(g)?
alina1380 [7]

Mass of H₂ needed to react with O₂ : 1.092 g

<h3>Further explanation</h3>

The concentration of a substance can be expressed in several quantities such as moles, percent (%) weight / volume,), molarity, molality, parts per million (ppm) or mole fraction. The concentration shows the amount of solute in a unit of the amount of solvent.

Reaction

O₂(g) + 2H₂(g) → 2H₂O(g)

mass of O₂ : 8.75 g

mol O₂(MW=32 g/mol) :

\tt \dfrac{8.75}{32}=0.273

From the equation, mol ratio of O₂ : H₂ = 1 : 2, so mol H₂ :

\tt \dfrac{2}{1}\times 0.273=0.546

Mass H₂ (MW=2 g/mol) :

\tt 0.546\times 2=1.092~g

4 0
3 years ago
Read 2 more answers
What is the longest wavelength in the Balmer series? (Hint: the Rydberg constant for Hydrogen is 1.096776×107 1/m, and the Balme
boyakko [2]

<u>Answer:</u> The longest wavelength of light is 656.5 nm

<u>Explanation:</u>

For the longest wavelength, the transition should be from n to n+1, where: n = lower energy level

To calculate the wavelength of light, we use Rydberg's Equation:

\frac{1}{\lambda}=R_H\left(\frac{1}{n_i^2}-\frac{1}{n_f^2} \right )

Where,

\lambda = Wavelength of radiation

R_H = Rydberg's Constant  = 1.096776\times 10^7m^{-1}

n_f = Higher energy level = n_i+1=(2+1)=3

n_i= Lower energy level = 2    (Balmer series)

Putting the values in above equation, we get:

\frac{1}{\lambda }=1.096776\times 10^7m^{-1}\left(\frac{1}{2^2}-\frac{1}{3^2} \right )\\\\\lambda =\frac{1}{1.5233\times 10^6m^{-1}}=6.565\times 10^{-7}m

Converting this into nanometers, we use the conversion factor:

1m=10^9nm

So, 6.565\times 10^{-7}m\times (\frac{10^9nm}{1m})=656.5nm

Hence, the longest wavelength of light is 656.5 nm

4 0
3 years ago
Lead (II)oxide+calcium metal=​
AfilCa [17]
I didn’t understand
3 0
3 years ago
Check my answers please! 1.Which of the following conditions increases the number of collisions between reactant molecules in a
NikAS [45]
<span>I was correct... 1 is adding more reactant molecules and 2 was decreasing in ch3br concentration over time </span>
7 0
3 years ago
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