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kotegsom [21]
3 years ago
6

The half-life of radioactive substance is 2.5 minutes. what fraction of the origional radioactive remains after 10 mins

Chemistry
1 answer:
saul85 [17]3 years ago
3 0
The answer is 1/16.

Half-life is the time required for the amount of a sample to half its value.
To calculate this, we will use the following formulas:
1. (1/2)^{n} = x,
where:
<span>n - a number of half-lives
</span>x - a remained fraction of a sample

2. t_{1/2} = \frac{t}{n}
where:
<span>t_{1/2} - half-life
</span>t - <span>total time elapsed
</span><span>n - a number of half-lives
</span>
So, we know:
t = 10 min
<span>t_{1/2} = 2.5 min

We need:
n = ?
x = ?
</span>
We could first use the second equation to calculate n:
<span>If:
t_{1/2} = \frac{t}{n},
</span>Then: 
n = \frac{t}{ t_{1/2} }
⇒ n = \frac{10 min}{2.5 min}
⇒ n=4<span>
</span>
Now we can use the first equation to calculate the remained fraction of the sample.
<span>(1/2)^{n} = x
</span>⇒ x=(1/2)^4
<span>⇒x= \frac{1}{16}</span>
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Which of the following statements are true regarding the dissociation of Al(NO3)3? Select more than one
Gelneren [198K]

Answer:

There will be one Al3+ ion.

There will be 3 NO3- ions

Explanation:

Dissociation equation:

Al(NO₃)₃   →  Al³⁺ + 3NO₃¹⁻

When aluminium nitrate dissociate it produces one silver ion (Al³⁺) and three (NO₃¹⁻) ions.

Properties of Al(NO₃)₃:

It is inorganic compound having molecular mass 169.87 g/mol.

It is white odor less compound.

Its density is 4.35 g/mL.

Its melting and boiling points are 120°C and 440°C.

It is soluble in water.

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It is used in the photographic films.

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4 0
2 years ago
A gas that exerts a pressure of
spayn [35]

Answer:

3.089 L

Explanation:

From the given information, provided that the no of moles and the temperature remains constant;

P_1 = 15.6 psi

V_1 = ???

P_2 = 25.43 psi

V_2 = 1.895 L

Using Boyle's law:

P_1V_1 =P_2V_2 \\ \\ V_1 = \dfrac{P_2V_2}{P_1} \\ \\  V_1 = \dfrac{25.43 \times 1.895}{15.6}  \\ \\ \mathbf{  V_1 = 3.089  \ L}

4 0
2 years ago
How can there be more than 1000 different atoms when there are only about 100 different elements?
Irina-Kira [14]
Um im pretty sure there are only about 100 different atoms...
7 0
2 years ago
A buffer is prepared containing 0.75 M NH3 and 0.20 M NH4 . Calculate the pH of the buffer using the Kb for NH3. g
denis-greek [22]

Answer:

pH=8.676

Explanation:

Given:

0.75 M NH_{3}

0.20 M NH_{4}

The objective is to calculate the pH of the buffer using the kb for NH_3

Formula used:

pOH=pka+log\frac{[salt]}{[base]}\\

pH=14-pOH

Solution:

On substituting salt=0.75 and base=0.20 in the formula

pOH=-log(1.77*10^{-5})+log\frac{0.75}{0.20}\\        =4.75+0.5740\\        =5.324

pH=14-pOH

On substituting the pOH value in the above expression,

pH=14-5.324

Therefore,

pH=8.676

3 0
3 years ago
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Strike441 [17]

Answer:

B

Explanation:

8 0
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