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2 years ago

Fossils provide evidence that

1 answer:

katrin2010 [14]2 years ago

7 0

Of these options, I'd say the third choice or "Many species of organisms that lived long ago are now extinct". I hope this helps :)

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A method used by the U.S. Environmental Protection Agency (EPA) for determining the concentration of ozone in air is to pass the

baherus [9]

Answer: 1. $9.08\times 10^{-6}$ moles

2. 90 mg

Explanation:

$O_3(g)+2NaI(aq)+H_2O(l) \rightarrow O_2(g)+I_2(s)+2NaOH(aq)$

According to stoichiometry:

1 mole of ozone is removed by 2 moles of sodium iodide.

Thus $4.54 \times 10^{-6}$ moles of ozone is removed by = $\frac{2}{1}\times 4.54 \times 10^{-6}=9.08\times 10^{-6}$ moles of sodium iodide.

Thus $9.08\times 10^{-6}$ moles of sodium iodide are needed to remove $4.54\times 10^{-6}$ moles of $O_3$

2. $\text{Number of moles of ozone}=\frac{0.01331g}{48g/mol}=0.0003moles$

According to stoichiometry:

1 mole of ozone is removed by 2 moles of sodium iodide.

Thus 0.0003 moles of ozone is removed by = $\frac{2}{1}\times 0.0003=0.0006$ moles of sodium iodide.

Mass of sodium iodide= $moles\times {\text {molar mass}}=0.0006\times 150g/mol=0.09g=90mg$ (1g=1000mg)

Thus 90 mg of sodium iodide are needed to remove 13.31 mg of $O_3$ .

3 0

2 years ago

Radio waves are ____________ waves

blsea [12.9K]

Answer: an electromagnetic wave of a frequency between about 104 and 1011 or 1012 Hz, as used for long-distance communication.

Explanation:

6 0

3 years ago

Read 2 more answers

Calculate the number of molecules in 210 grams of H2O

spin [16.1K]

H2O=18.01g/mole. 210g divided by 18.01g/mole=11.653mole. 1 mole has 6.22x10^23 molecules. So there is 11.653x(6.22x10^23) molecules. Just multiply 11.653 by 6.22. Then put it as answerx10^23 molecules

4 0

3 years ago

5. Base your answer to the following question on the

elixir [45]

Answer:

B) 2Crº + 6e- --> 2Cr3+

Explanation:

The process of oxidation is where electrons are lost. Thus, out of the 2 ions that change charge(Cr and Cu), we must choose the one where the oxidation number increases(which means electrons are lost). Cr goes from an oxidation number of 0 to an oxidation number of 3+, while Cu goes from an oxidation number of 2+ to 0. Thus, we are looking at the half reaction for Cr. Half reactions never have subtracting electrons, so the answer must be B. I am assuming that last plus should be a -->

4 0

3 years ago

Read 2 more answers

It refers to a charged particle or atom.

Kay [80]

<h2><u>QUE</u><u>STION</u></h2>

It refers to a charged particle or atom.

<u>A.</u><u> </u><u>molecule</u>

B. bromine

C. potassium

D. sulfur

<h2><u>ANSWER</u></h2>

<h3><u>C</u><u>.</u><u> </u><u>pottasium</u></h3>

7 0

2 years ago