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Dima020 [189]
3 years ago
9

The half life of a certain radioactive element is 800 years. How old is an object if only 12.5% of radioactive atoms in it remai

ns?
Chemistry
1 answer:
Levart [38]3 years ago
6 0

Given,  half life of a certain radioactive element = 800 years.

Amount of substance remaining at time t = 12.5%

Lets consider the initial amount of the radioactive substance  = 100%

Using the half life equation:

A = A₀(1/2)^t/t₁/₂

where A₀ is the amount of radioactive substance at time zero and A is the amount of radioactive substance at time t, and t₁/₂ is the half-life of the radioactive substance.

Plugging the given data into the half life equation we have,

12.5 = 100 . (1/2)^t/800

12.5/100 = (1/2)^t/800

0.125 = (0.5)^t/800

(0.5)^3 = (0.5)^t/800

3 = t/800

t = 2400 years

Thus the object is 2400 years  old.



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The fact that you get any products at all means that the reactants will become products.  Just who is favored has to be looked at very carefully. The products start very near 0. They go up until their concentration at equilibrium. When the reach equilibrium, the products have increased to 17. The reactants have dropped from 40 to 27. By a narrow margin, I would say the products are favored.

C is incorrect. There are still reactants left.  

E is incorrect. the reactants started out with a concentration of 40. The reaction is not instantaneous.  The concentration was highest at 40 or right at the beginning. This assumes that the reactants were mixed and the products were produced and the water/liquid amount has not changed.

B is incorrect. The concentration of the reactants is higher at equilibrium.

A is wrong. It is product favored.

I'm getting none of the above.

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AgBr is insoluble (very). You'd have to work very hard to get them to separate into their elemental form. Just putting AgBr in water isn't enough. Lots of heat and lots of electricity are needed to get the elemental form.

I suppose you should pick B. Mass must be preserved. But if you balanced the equation, it would work with heat and electricity.



3 0
3 years ago
Read 2 more answers
How can you increase the amount of work done when you lift a book explain
Gnoma [55]
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  • F = mg

and, the change in the position of the book that is Δx (Height)

→ Δx = Final position - Initial position

which is only the height, then the amount of work done will be calculated by :

W= mgh

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4 0
2 years ago
A gas has a pressure of 3.16 atm at STP. I have decided to transfer it to a container that is 3 times larger than the original v
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Answer:

<u>The new pressure is 1.0533 atm</u>

<u></u>

Explanation:

According  to<u> Boyle's Law :</u> The Pressure of fixed amount of gas is inversely proportional to Volume at constant temperature.

PV = Constant

P1V1 = P2V2

P_{1}V_{1}=P_{2}V_{2}.....(1)

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Accprding to question ,

V1 = V

V2 = 3 V

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5 0
2 years ago
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miskamm [114]

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Answer:

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