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Setler79 [48]
3 years ago
5

Select the correct responses to the questions from the drop-down menu.

Chemistry
2 answers:
inn [45]3 years ago
6 0

Answer:

b,a

Explanation:

Damm [24]3 years ago
5 0

Answer: Fossils, Precambrian

Explanation:)

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How can endangered species be saved ?
labwork [276]

Answer:

There are lots of methods.

Explanation:

Usually, animals like pandas live a shorter lifespan in the wild than in captivity. A little fact, there is only one brown panda in the entire world, so it would be very, very rare to see one. The Smithsonian National Zoo, for example, are working to protect pandas, as well as other species.

5 0
3 years ago
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The useful metal manganese can be extracted from the mineral rhodochrosite by a two-step process.... In the first step, manganes
frez [133]

Answer : The mass of MnCO_3 required are, 35 kg

Explanation :

First we have to calculate the mass of MnO_2.

The first step balanced chemical reaction is:

2MnCO_3+O_2\rightarrow 2MnO_2+2CO_2

Molar mass of MnCO_3 = 115 g/mole

Molar mass of MnO_2 = 87 g/mole

Let the mass of MnCO_3 be, 'x' grams.

From the balanced reaction, we conclude that

As, (2\times 115)g of MnCO_3 react to give (2\times 87)g of MnO_2

So, xg of MnCO_3 react to give \frac{(2\times 87)g}{(2\times 115)g}\times x=0.757xg of MnO_2

And as we are given that the yield produced from the first step is, 65 % that means,

60\% \text{ of }0.757xg=\frac{60}{100}\times 0.757x=0.4542xg

The mass of MnO_2 obtained = 0.4542x g

Now we have to calculate the mass of Mn.

The second step balanced chemical reaction is:

3MnO_2+4Al\rightarrow 3Mn+2Al_2O_3

Molar mass of MnO_2 = 87 g/mole

Molar mass of Mn = 55 g/mole

From the balanced reaction, we conclude that

As, (3\times 87)g of MnO_2 react to give (3\times 55)g of Mn

So, 0.4542xg of MnO_2 react to give \frac{(3\times 55)g}{(3\times 87)g}\times 0.4542x=0.287xg of Mn

And as we are given that the yield produced from the second step is, 80 % that means,

80\% \text{ of }0.287xg=\frac{80}{100}\times 0.287x=0.2296xg

The mass of Mn obtained = 0.2296x g

The given mass of Mn = 8.0 kg = 8000 g     (1 kg = 1000 g)

So, 0.2296x = 8000

x = 34843.20 g = 34.84 kg = 35 kg

Therefore, the mass of MnCO_3 required are, 35 kg

4 0
3 years ago
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PLSS HELP! The gas carbon dioxide is a pure substance. Which of the following is true about carbon dioxide? (4 points)
Nadusha1986 [10]

Answer:

The answer is option A..

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Name 2 ways plants reproduce. give an example of each way.
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Plants can reproduce through either sexual or asexual means. Sexual reproduction involves pollination helped by wind and or insects. Asexual reproduction involves tubers, bulbs and runners known as rhizomes and stolons as well as cuttings taken by humans.
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Different visible waves show different colors

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