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Elis [28]
3 years ago
6

A potassium-40 sample starts with 50 atoms, and 1.25 billion years later, there are 25 atoms. What is the half-life of potassium

-40?
A. 2.5 billion years
B. 25 years
C. 40 years
D. 1.25 billion years
Chemistry
1 answer:
guapka [62]3 years ago
5 0
D. 1.25 billion years
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The mass of a radioactive substance follows a continuous exponential decay model, with a decay rate parameter of 8.1% per day. f
Elanso [62]
The general equation for radioactive decay is;
N = N₀e^(-λt)
x - decay constant (λ) - rate of decay 
t-  time 
N - amount remaining after t days , since we are calculating the half life, amount of time it takes for the substance to to be half its original value, its N₀/2
N₀ - amount initially present 
substituting the values 
N₀/2 = N₀e^(-0.081t)
0.5 = e^(-0.081t)
ln (0.5) = -0.081t
-0.693 = -0.081t
t = 0.693 / 0.081 
  = 8.55
half life of substance is 8.55 days 
5 0
3 years ago
consider this reaction at equilibrium at a total pressure: 2h2o(g) o2(g) 2h2o2(g) suppose the volume of this system is twice its
Daniel [21]

The total pressure when the new equilibrium is stabilized is half of the initial pressure of the system.

The given chemical reaction at a stable equilibrium is,

2H₂O(g)+O₂(g) = 2H₂O₂(g)

According to the ideal gas equation,

PV = nRT

P is pressure,

V is volume,

n is moles

R is gas constant,

T is temperature.

Assuming the temperature is constant.

If the volume of the system is twice the initial volume then the total pressure at the new equilibrium can be found out as,

P₁V₁ = P₂V₂

Where, P₁ and V₁ are initial volume and pressure while P₂ and V₂ are final pressure and volume.

If V₂ = 2V₁,

P₂ = P₁/2

So, the final total pressure will be half of the initial pressure.

To know more about equilibrium, visit,

brainly.com/question/517289

#SPJ4

5 0
10 months ago
How are silicate minerals different from nonsilicate minerals
tino4ka555 [31]

Answer: The main difference between silicate minerals and nonsilicate minerals is that silicate minerals are composed of silicate groups whereas Nonsilicate minerals have no silicate groups.

Explanation:

7 0
3 years ago
The molar mass of H2O is 18.01 g/mol. The molar mass of O2is 32.00 g/mol. What mass of H2O,in grams, must react to produce 50.00
N76 [4]
Answer is: mass of water is 56.28 grams.
Chemical reaction: 2H₂O → 2H₂ + O₂.
m(O₂) = 50.00 g.
n(O₂) = m(O₂) ÷ M(O₂).
n(O₂) = 50 g ÷ 32 g/mol.
n(O₂) = 1.5625 mol.
From chemical reaction: n(O₂) : n(H₂O) = 1 : 2.
n(H₂O) = 2 · 1.5625 mol.
n(H₂O) = 3.125 mol.
m(H₂O) = n(H₂O) · M(H₂O).
m(H₂O) = 3.125 mol · 18.01 g/mol.
m(H₂O) = 56.28 g.
7 0
3 years ago
Read 2 more answers
The measurement 3.8 x 10^3 g could also be written as
solmaris [256]

Right now it's written in scientific notation, so you can just move the decimal place in 3.8 to the right 3 times (as it is times 10 to the third power) to get 3,800g.

5 0
3 years ago
Read 2 more answers
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