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3 years ago

Scientist think that many species have one common ancestor. Which answer choice best tells why scientists think this way?

Chemistry

1 answer:

BigorU [14]3 years ago

3 0

Answer:

homologous structures.

Explanation:

If you look at many different organisms, you will see similar structures. Like humans have a forearm, birds have a wing, whales have fins, leopards have legs. The bones evolvolved to fit the animal

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Consider a solution containing 0.100 M fluoride ions and 0.126 M hydrogen fluoride. The concentration of fluoride ions after the

Nataliya [291]

Answer: The concentration of fluoride ions after the addition of 9.00 mL of 0.0100 M HCl to 25.0 mL of this solution is 0.0709 M.

Explanation:

Given: Concentration of hydrogen fluoride = 0.126 M

Concentration of fluoride ions = 0.1 M

Volume of HCl = 9.0 mL

Concentration of HCl = 0.01 M

Volume of HCl = 25.0 mL

Moles of $F^{-}$ ions are calculated as follows.

$Moles of F^{-} = molarity \times volume\\= 0.1 M \times 0.025 L\\= 0.0025 mol$

Moles of HF are as follows.

$Moles of HF = Molarity \times Volume\\= 0.126 M \times 0.025 L\\= 0.00315 mol$

Moles of HCl are as follows.

$Moles of HCl = Molarity \times volume\\= 0.01 M \times 0.009 L\\= 0.00009 mol$

Now, reaction equation with initial and final moles will be as follows.

$H^{+} + F^{-} \rightarrow HF$

Initial: 0.00009 0.0025 0.00315

Equilibrium: (0.0025 - 0.00009) (0.00315 + 0.00009)

= 0.00241 = 0.00324

Total volume = (9.00 mL + 25.0 mL) = 34.0 mL = 0.034 L

Hence, concentration of fluoride ions is calculated as follows.

$Concentration = \frac{moles}{volume}\\= \frac{0.00241 mol}{0.034 L}\\= 0.0709 M$

Thus, we can conclude that concentration of fluoride ions after the addition of 9.00 mL of 0.0100 M HCl to 25.0 mL of this solution is 0.0709 M.

7 0

3 years ago

Please help due today!

TEA [102]

for the first one it is B OR THE SECOND OPTION

8 0

3 years ago

All light waves can be described in terms of their speed, frequency, and_____

coldgirl [10]

I’m not really sure just trying to get points but maybe it’s length

4 0

3 years ago

At the Henry's Law constant for carbon dioxide gas in water is . Calculate the mass in grams of gas that can be dissolved in of

Dvinal [7]

The question is incomplete, here is the complete question:

At 25°C Henry's Law constant for carbon dioxide gas in water is 0.031 M/atm . Calculate the mass in grams of gas that can be dissolved in 425. mL of water at 25°C and at a partial pressure of 2.92 atm. Round your answer to 2 significant digits.

<u>Answer:</u> The mass of carbon dioxide that can be dissolved is 1.7 grams

<u>Explanation:</u>

To calculate the molar solubility, we use the equation given by Henry's law, which is:

$C_{CO_2}=K_H\times p_{CO_2}$

where,

$K_H$ = Henry's constant = $0.031M/atm$

$C_{CO_2}$ = molar solubility of carbon dioxide gas

$p_{CO_2}$ = partial pressure of carbon dioxide gas = 2.92 atm

Putting values in above equation, we get:

$C_{CO_2}=0.031M/atm\times 2.92 atm\\\\C_{CO_2}=0.0905M$

To calculate the mass of solute, we use the equation used to calculate the molarity of solution:

$\text{Molarity of the solution}=\frac{\text{Mass of solute}\times 1000}{\text{Molar mass of solute}\times \text{Volume of solution (in mL)}}$

Given mass of carbon dioxide = ? g

Molar mass of carbon dioxide = 44 g/mol

Molarity of solution = $0.0905mol/L$

Volume of solution = 425 mL

Putting values in above equation, we get:

$0.0905mol/L=\frac{\text{Mass of carbon dioxide}\times 1000}{44g/mol\times 425}\\\\\text{Mass of solute}=\frac{44\times 425\times 0.0905}{1000}=1.7g$

Hence, the mass of carbon dioxide that can be dissolved is 1.7 grams

8 0

3 years ago

Explain what is cellular growth and repair? Why is it important?

HACTEHA [7]

Answer:

Cell growth usually refers to cell proliferation, the increase in cell numbers that occurs through repeated cell division. Cell growth can also refer to the enlargement of cell volume, which can take place in the absence of cell division. As living things grow, some cells die or become damaged and need replacements. Some single-celled organisms use a type of mitosis as their only form of reproduction. In multicellular organisms, cell division allows individuals to grow and change by expanding the number of total cells.

Hope this helps!!!

3 0

3 years ago