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Vesna [10]
3 years ago
10

If you have 100 grams of a radioactive isotope with a half life of 10 years how much of the isotope will you have left after 20

years
Chemistry
1 answer:
Cerrena [4.2K]3 years ago
3 0

Hey there!

A half-life means after a certain amount of time, half of that substance will be gone/changed after that time.

There are two half lives in 20 years because 20 ÷ 10 = 2.

So, we divide the 100g sample in half 2 times.

100 ÷ 2 = 50

50 ÷ 2 = 25

There will be 25g of the radioactive sample remaining after two half lives.

Hope this helps!

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Write the formula two atom of iron and three atoms of oxygen​
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Answer:

Fe2O3 is the formula this is your correct answer

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How many valence electrons does B (boron) have?<br> A. 13<br> B. 5<br> C. 10<br> D. 3
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Answer:

Boron has 3 valence electrons

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The human body excretes nitrogen in the form of urea, NH₂CONH₂. The key step in its biochemical formation is the reaction of wat
Misha Larkins [42]

Mass perventage of nitrogen in urea, arginine, ornithine is   46.67%, 32.2%,21% respectively.

What is Mass perventage ?

Mass percentage is one way of representing the concentration of an element in a compound or a component in a mixture. Mass percentage is calculated as the mass of a component divided by the total mass of the mixture, multiplied by 100.

Molecular mass of urea (NH2CONH2) is= 2× (Atomic mass of N ) + 4 × (Atomic mass of H) + (Atomic mass of C) (Atomic mass of O) = 60

Mass percentage of N = Total mass of N atoms in the compoundMass of compound×100=2860×100=46.67%

chemical formula for arginine is C6H14N4O2

molar mass of C6H14N4O2=174g/mol

moles of N atoms in C6H14N4O2=4

mass of N atoms=14*4=56g

mass percent of N in C6H14N4O2=(56/174)*100=32.2%

the chemical formula for ornithine is C5H12N2O2

molar mass of C5H12N2O2=132g/mol

moles of N atoms in C5H12N2O2=2

mass of N atoms in C5H12N2O2=2*14=28

mass percent of N in C5H12N2O2=(28/132)*100=21%

To learn more about urea click on the link below:

brainly.com/question/17812875

#SPJ4

7 0
1 year ago
Will marks brainly if it isn’t a copied answer!!!
Neporo4naja [7]

What kind of control like scientific?

5 0
3 years ago
Read 2 more answers
Consider the reaction of peroxydisulfate ion (S2O2−8) with iodide ion (I−) in aqueous solution: S2O2−8(aq)+3I−(aq)→2SO2−4(aq)+I−
kolbaska11 [484]

Answer:

r = 3.61x10^{-6} M/s

Explanation:

The rate of disappearance (r) is given by the multiplication of the concentrations of the reagents, each one raised of the coefficient of the reaction.

r = k.[S2O2^{-8} ]^{x} x [I^{-} ]^{y}

K is the constant of the reaction, and doesn't depends on the concentrations. First, let's find the coefficients x and y. Let's use the first and the second experiments, and lets divide 1º by 2º :

\frac{r1}{r2} = \frac{0.018^{x} x0.036^{y} }{0.027^xx0.036^y}

\frac{2.6x10^{-6}}{3.9x10^{-6}} = (\frac{0.018}{0.027})^xx(\frac{0.036}{0.036})^y

0.67 = 0.67^x

x = 1

Now, to find the coefficient y let's do the same for the experiments 1 and 3:

\frac{r1}{r3} = \frac{0.018x0.036^y}{0.036x0.054^y}

\frac{2.6x10^{-6}}{7.8x10^{-6}} = (\frac{0.018}{0.036})x(\frac{0.036}{0.054})^y

0.33 = 0.5x 0.67^y

0.67 = 0.67^y

y = 1

Now, we need to calculate the constant k in whatever experiment. Using the first :

2.6x10^{-6} = kx0.018x0.036kx6.48x10^{-4} = 2.6x10^{-6}

k = 4.01x10^{-3} M^{-1}s^{-1}[/tex]

Using the data given,

r = 4.01x10^{-3}x1.8x10^{-2}x5.0x10^{-2}

r = 3.61x10^{-6} M/s

7 0
3 years ago
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