Exactly how much time must elapse before 16 grams of potassium-42decays, leaving 2 grams of the original isotope?(1) 8 × 12.4 hours (3) 3 × 12.4 hours(2) 2 × 12.4 hours (4) 4 × 12.4 hours

Answers

Answer 1

Answer: The answer is (3) 3 × 12.4 hours

To calculate this, we will use two equations:
$(1/2) ^(n) =x$
$t_(1/2) = (t)/(n)$
where:
n - number of half-lives
x - remained amount of the sample, in decimals
$t_(1/2)$ - half-life length
t - total time elapsed.

First, we have to calculate x and n. x is remained amount of the sample, so if at the beginning were 16 grams of potassium-42, and now it remained 2 grams, then x is:
2 grams : x % = 16 grams : 100 %
x = 2 grams × 100 percent ÷ 16 grams
x = 12.5% = 0.125

Thus:
$(1/2) ^(n) =x$
$(0.5) ^(n) =0.125$
$n*log(0.5)=log(0.125)$
$n= (log(0.5))/(log(0.125))$
$n=3$

It is known that the half-life of potassium-42 is 12.36 ≈ 12.4 hours.
Thus:
$t_(1/2) = 12.4$
$t_(1/2) *n = t$
$t= 12.4*3$

Therefore, it must elapse 3 × 12.4 hours before 16 grams of potassium-42 decays, leaving 2 grams of the original isotope

Answer 2

Answer:

Answer:

The answer is (3) 3 × 12.4 hours

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Answers

Answer:

$\boxed{3 * 10^(23)}$

Explanation:

1 mol of helium contains 6.022 × 10²³ atoms

$\text{Atoms of He} =\text{0.5 mol He} * \frac{ 6.022 * 10^(23) \text{ atoms He}}{\text{1 mol He}}= 3 * 10^(23) \text{ atoms He}$

The balloon contains $\boxed{3 * 10^(23) \text{ atoms of He}}$ .

69.253 helium particles are in the balloon.

What is helium particles?

Helium is composed of two electrons bound by the electromagnetic force to a nucleus containing two protons along with either one or two neutrons, depending on the isotope, held together by the strong force. Unlike for hydrogen, a closed-form solution to the Schrodinger equation for the helium atom has not been found.

A helium atom is an atom of the chemical element helium. Helium is composed of two electrons bound by the electromagnetic force to a nucleus containing two protons along with either one or two neutrons, depending on the isotope, held together by the strong force. Unlike for hydrogen, a closed-form solution.

Helium is the element which you can find on the upper right side of the periodic table with atomic number 2. It comes first amongst the family of the noble gases. Helium falls under inert gas since its outermost electron orbital is full with two electrons.

The answer is 69.253.

Learn more about helium, refer:

brainly.com/question/25306199

#SPJ2

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Answers

Mass number on the periodic table is the bigger number. For example, Hydrogen's atomic number is 1, and mass number is 1.008. The mass number (rounded) is the total number of neutrons and protons in an atom.

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Answers

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Answers

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Explanation :

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Answers

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