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2 years ago

How does the law of conservation of energy relate to the idea of system and surrounding ?

1 answer:

7 0

energy is completely different from energy conservation. Energy conservation means saving energy through such things as insulating your home or using public transportation; generally it saves you money and helps the planet. The conservation of energy has nothing to do with saving energy: it's all about where energy

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The half-life of cesium-137 is 30 years. Suppose we have a 180 mg sample. Find the mass that remains after t years. Let y(t) be

Stels [109]

Explanation:

1) Initial mass of the Cesium-137= $N_o$ = 180 mg

Mass of Cesium after time t = N

Formula used :

$N=N_o\times e^{-\lambda t}\\\\\lambda =\frac{0.693}{t_{\frac{1}{2}}}$

Half life of the cesium-137 = $t_{1/2}=30 years[p/tex]where,
[tex]N_o$ = initial mass of isotope

N = mass of the parent isotope left after the time, (t)

$t_{\frac{1}{2}}$ = half life of the isotope

$\lambda$ = rate constant

$N=N_o\times e^{-(\frac{0.693}{t_{1/2}})\times t}$

Now put all the given values in this formula, we get

$N=180mg\times e^{-\frac{0.693}{30 years}\times t}$

Mass that remains after t years.

$N=180 mg\times e^{0.0231 year^{-1}\times t}$

Therefore, the parent isotope remain after one half life will be, 100 grams.

t = 70 years

$N_o=180 mg$

$t_{1/2}= 30 yeras$

$N=180mg\times e^{-\frac{0.693}{30 years}\times 70 years}$

N = 35.73 mg

35.73 mg of cesium-137 will remain after 70 years.

$N_o=180 mg$

$t_{1/2}= 30 yeras$

N = 1 mg

t = ?

$1 mg =180mg\times e^{-\frac{0.693}{30 years}\times t}$

$\frac{-30 year}{0.693}\times \ln \frac{1 mg}{180 mg}=t$

t = 224.80 years ≈ 225 years

After 225 years only 1 mg of cesium-137 will remain.

7 0

3 years ago

Someone help please I don’t know the answer to the question I meeed help

mihalych1998 [28]

Answer: 143.3

137+115+104+263+98 divided by 5.Which gives us 143.3

5 0

2 years ago

Which of the following properties of an unknown substance would allow it to be classified as a mixture? The unknown substance

Nadya [2.5K]

Answer:

D. has different properties when sampled in different areas.

Explanation:

The general property of a mixture says that each substance or component in a mixture has its individual or different property which can be separated on the basis of different methods.

Such as a mixture of oil and water is a heterogeneous mixture and have different properties or different densities, which helps them to be sampled in different areas.

Hence, the correct answer is "D".

6 0

2 years ago

Compare how entropy changes for the following two systems:

postnew [5]

System A undergoes an increase in entropy while system B undergoes a decrease in entropy.

Entropy is the degree of disorderliness of a system. The entropy of a system depends on the number of particles present in the system as well as the state of matter.

Entropy is increased when solid particles dissolve in water because more particles are produced thereby increasing the level of disorderliness in the system.

On the other hand, when vapor is condensed, the degree of disorderliness decreases as gases are converted to liquids.

Learn more: brainly.com/question/13146879

7 0

2 years ago

Plants like the ones shown in the picture, that use seeds, flowers, or fruit for reproduction are A) flowering. B) invertebrates

tensa zangetsu [6.8K]

Plants like the ones shown in the picture, that use seeds, flowers, or fruit for reproduction are A) flowering.

The picture shows flowering plants that are using seeds, flowers or fruits and they are called flowering plant .

So the answer here is A) flowering.

Plants like the ones shown in the picture, that use seeds, flowers, or fruit for reproduction are A) flowering.

7 0

2 years ago

Read 2 more answers