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borishaifa [10]
3 years ago
15

A sample originally contained 1.28 g of a radioisotope. It now contains 1.12 g of its daughter isotope.

Chemistry
2 answers:
dexar [7]3 years ago
4 0
The answer is 3.

<span>The relation between number of half-lives (n) and decimal amount remaining (x) can be expressed as:

</span>(1/2) ^{n} =x

We need to calculate n, but we need x to do that. To calculate what p<span>ercentage of a radioactive species would be found as daughter material, we must calculate what amount remained:
1.28 -</span> 1.12 = 0.16

If 1.28 is 100%, how much percent is 0.16:
1.28 : 100% = 0.16 : x
x = 12.5% 
Presented as decimal amount:
x = 0.125


Now, let's implement this in the equation: 

<span>(1/2) ^{n} =0.125
</span>
Because of the exponent, we will log both sides of the equation:
n * log(1/2) = log(0.125)
n = \frac{log(0.125)}{log(1/2)}
<span>n = \frac{log(0.125)}{log(0.5)}
</span>n= \frac{-0.903}{-0.301}
n = 3

Therefore, 3 half-lives have passed <span> since the sample originally formed.</span>
8_murik_8 [283]3 years ago
3 0

Answer:

3

Explanation:

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Consider the following ionic compounds: CdCO3, Na2S, PbSO4, (NH4)3PO4, and Hg2Cl2. Which compounds will be soluble when added to
k0ka [10]

Answer:

Na2S, (NH4)3PO4

Explanation:

We can decide what compounds are soluble by considering the solubility rules that apply.

CdCO3 is not soluble in water because all carbonates are insoluble except those of ammonium, sodium and potassium.

Na2S is soluble in water because all sulphides are insoluble except those of sodium, potassium and ammonium.

PbSO4 is insoluble in water because all sulphates are soluble except those of lead and barium. The sulphate of calcium is only slightly soluble in water.

(NH4)3PO4 is soluble in water because all phosphates are insoluble except those of sodium, potassium and ammonium.

Hg2Cl2 is insoluble in water because all chlorides are soluble except those of lead, mercury II and silver.

7 0
3 years ago
Imagine that you are an astronomer and you have detected a star that has a temperature of about 3700 Kelvin, and a luminosity of
Alex_Xolod [135]

Answer:

<em><u>Annie Jump Cannon entered Wellesley College in Massachusetts in 1880 to study astronomy. She became interested in stellar spectroscopy, the process of breaking light from stars down into its component colors so the various elements can be identified. After suffering from scarlet fever, which left her hearing impaired, she earned her master�s degree and then continued her studies at Radcliffe College. She became an assistant at the Harvard College Observatory, the first observatory to include women as staff members. During her career, she observed, classified, and analyzed the spectra of some five hundred thousand stars, assigning each one its place in the sequence O, B, A, F, G, K, and M. In 1911 she almost became a faculty member at Harvard but the university officials refused to promote a woman to such high status. So she became the curator of astronomical photographs, earning a salary of twelve hundred dollars a year. Finally, in 1936, Harvard hired her as a permanent faculty member. She was seventy-three years old at the time.</u></em>

<em><u>Annie Jump Cannon entered Wellesley College in Massachusetts in 1880 to study astronomy. She became interested in stellar spectroscopy, the process of breaking light from stars down into its component colors so the various elements can be identified. After suffering from scarlet fever, which left her hearing impaired, she earned her master�s degree and then continued her studies at Radcliffe College. She became an assistant at the Harvard College Observatory, the first observatory to include women as staff members. During her career, she observed, classified, and analyzed the spectra of some five hundred thousand stars, assigning each one its place in the sequence O, B, A, F, G, K, and M. In 1911 she almost became a faculty member at Harvard but the university officials refused to promote a woman to such high status. So she became the curator of astronomical photographs, earning a salary of twelve hundred dollars a year. Finally, in 1936, Harvard hired her as a permanent faculty member. She was seventy-three years old at the time.Astronomers now realize that everything which appears to distinguish one star from another - temperature, luminosity, size, life span -- is determined almost entirely by one factor: the star's mass. The main sequence along the HR diagram is not a singular evolutionary path, as many had thought, but a portrait of the sky at one moment in time of stars with varying masses.</u></em>

<em><u>Annie Jump Cannon entered Wellesley College in Massachusetts in 1880 to study astronomy. She became interested in stellar spectroscopy, the process of breaking light from stars down into its component colors so the various elements can be identified. After suffering from scarlet fever, which left her hearing impaired, she earned her master�s degree and then continued her studies at Radcliffe College. She became an assistant at the Harvard College Observatory, the first observatory to include women as staff members. During her career, she observed, classified, and analyzed the spectra of some five hundred thousand stars, assigning each one its place in the sequence O, B, A, F, G, K, and M. In 1911 she almost became a faculty member at Harvard but the university officials refused to promote a woman to such high status. So she became the curator of astronomical photographs, earning a salary of twelve hundred dollars a year. Finally, in 1936, Harvard hired her as a permanent faculty member. She was seventy-three years old at the time.Astronomers now realize that everything which appears to distinguish one star from another - temperature, luminosity, size, life span -- is determined almost entirely by one factor: the star's mass. The main sequence along the HR diagram is not a singular evolutionary path, as many had thought, but a portrait of the sky at one moment in time of stars with varying masses.Below is a version of the Hertzsprung-Russell diagram, which shows how the</u></em>

Explanation:

MARK ME AS A BRAINLIST PLZ

3 0
2 years ago
What is the theoretical yield of sodium chloride for the reaction of 55.0 g na with 67.2 g cl2?
lozanna [386]
The chemical reaction would be written as:

2Na + Cl2 = 2NaCl

Since we are given the amounts of the reactants available for reaction, we have to determine the limiting reactant. And use this amount to calculate for the theoretical yield.

55 g Na ( 1 mol / 22.99 g ) = 2.39 mol Na
67.2 f Cl2 ( 1 mol / 70.9 g ) = 0.95 mol Cl2

Therefore, the limiting reactant would be Cl2 since it is the one consumed completely.

0.95 Cl2 ( 1 mol NaCl / 1 mol Cl2) = 0.95 NaCl produced from the reaction
7 0
3 years ago
Given 6.23 mol Al find the atoms of Al
swat32

Answer:

The answer is

<h3>3.75 × 10²⁴ atoms of Al</h3>

Explanation:

To find the number of atoms of Al given it's number of moles we use the formula

<h3>N = n × L</h3>

where n is the number of moles

N is the number of entities

L is the Avogadro's constant which is

6.02 × 10²³ entities

From the question

n = 6.23 mol

We have

N = 6.23 × 6.02 × 10²³

We have the final answer as

<h3>3.75 × 10²⁴ atoms of Al</h3>

Hope this helps you

3 0
3 years ago
Name the four states of matter, and a characteristic to describe each.
Trava [24]

Answer:

solid particles are tightly held.

liquid particles have perfectly inelastic collisions

gas move in constant random motion

vapour

7 0
3 years ago
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