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2 years ago

Why are animals so impportant to our lifes

Chemistry

2 answers:

ivann1987 [24]2 years ago

5 0

Answer:

Animals are important because without them we wouldnt have any food

Explanation:

Greeley [361]2 years ago

4 0

Domesticated animals give us food, fiber and leather.

Wild animals, birds, fish, insects are important to from the web of activity in a functioning ecosystem.

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How much heat is absorbed when 30.00 g of C(s) reacts in the presence of excess SO2(g) to produce CS2(l) and CO(g) according to

Gnoma [55]

Answer:

120.0 kJ

Explanation:

First we convert the given mass of C to moles:

30.00 g C ÷ 12g/mol = 2.5 mol

The ΔH° value given by the problem, is the heat absorbed when 5 moles of C react.

So when we have<u> half the moles of C</u> (2.5 instead of 5.0), t<u>he heat absorbed will also be half</u>, thus the answer is:

239.9 kJ / 2 = 120.0 kJ

4 0

3 years ago

Characteristics of a substance that describe its' ability to change into a different substance are called?

Reika [66]

A characteristic of a pure substance that describes its ability to change into different substances. chemical change.

A change that occurs when one or more substances change into entirely new substances with different properties. physical property.

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2 years ago

Where are atoms that tend to gain electrons located in the periodic table of the elements?

Alex777 [14]

Gaining electrons would mean that it is near the stable octet, so it needs more.

Right side would be the answer

7 0

2 years ago

Which part of a bird's body is least likely to be preserved as a fossil? A. skeleton B. feathers C. skin D. internal organs E. b

Neporo4naja [7]

D. Internal organs, Organs will break down and be eaten by bugs and such postmortem

7 0

2 years ago

Read 2 more answers

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