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3 years ago

Why does a tadpole reabsorb its tail into its body?

Chemistry

2 answers:

vladimir1956 [14]3 years ago

4 0

The cells mutated is the answer

adelina 88 [10]3 years ago

3 0

Answer:

The cells mutated.

Explanation:

Lysosomes is the cell that digest the unwanted materials in the cytoplasm.

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Which of the statements regarding alcohols and ethers are true? 1-Propanol is more likely to be a liquid at 50 °C50 °C than is m

irina [24]

Answer:

Following statements are true:

1-Propanol is more likely to be a liquid at 50 than is methoxyethane (ethyl methyl ether).

Alcohol molecules can form hydrogen bonds among themselves;ether molecules cannot

Explanation:

1-Propanol is more likely to be a liquid at 50 than is methoxyethane (ethyl methyl ether).

This is true

Propanol has a boiling temperature (this is the temperature at which the vapor pressure of a liquid equals the pressure surrounding the liquid and the liquid changes into a vapor) of 97-98 °C while methoxyethane a boiling point of 7.4 °C.

This means at 50 °C propanol is liquid but methoxyethane at 50°C is a gas.

Methoxyethane (ethyl methyl ether) is more soluble in water than is 1-propanol.

This false:

Propanol has a hydrogen bonding. The OH on the alcohol can form a hydrogen bond (as a hydrogen acceptor and donor). Water can hydrogen bond. This means alcohol is will disolve in water. ( Remember Like dissolves like). So, when you have a molecule that can act as a donor and acceptor you end up with a much better interaction with water and end up with something that is more miscible. Ethers are only acceptors since they do not have a hydrogen attached to the oxygen. So, they can only accept a proton from water.

Methoxyethane (ethyl methyl ether) is more likely to be a liquid at 50 °C50 °C than is 1-propanol

This is false because propanol has a boiling temperature (this is the temperature at which the vapor pressure of a liquid equals the pressure surrounding the liquid and the liquid changes into a vapor) of 97-98 °C while methoxyethane a boiling point of 7.4 °C.

This means at 50 °C propanol is liquid but methoxyethane at 50°C is a gas.

Alcohol molecules can form hydrogen bonds among themselves;ether molecules cannot

This is true because:

Ether molecules cannot form hydrogen bonding between themselves because the oxygen atom is attached to 2 alkyl or aryl groups R-O-R, e.g diethyl ether, or Ar-O-Ar, such as diphenylether (C6H5)2O

C2H5-O-C2H5,m or dimethyl ether CH3—O-CH3. however they can between ether molecules and other molecules containing hydrogen atoms, such as alcohols, CH3OH. Any molecule with the hydrogen attached to a strongly electronegative element e.g Nitrogen or fluorine.

Methoxyethane (ethyl methyl ether) has a higher boiling point than 1-propanol.

This is false: Methoxyethane has a boiling point of 7.4 °C while propanol has a boiling point of 97-98 °C. This can be shown because at roomtemperature Methoxyethane is a gas but propanol is a liquid.

6 0

3 years ago

A scientist wants to use a model to help present the results of his detailed scientific investigation

Brilliant_brown [7]

because the model makes the concepts easier to understand

Explanation:

A model would be useful because they make concepts easier to understand.

Models are abstractions of the real world.

Scientists use model to make concepts easier to understand
Models take parts of the real world and simulates them.
They help remove the ambiguity that might be associated with studying the real world.

Learn more:

Model brainly.com/question/5012266

#learnwithbrainly

6 0

3 years ago

21. For each of the following precipitation reactions,

Phantasy [73]

I would say B.HS(aq)+NiSO4(aq)

6 0

3 years ago

In the laboratory, hydrogen gas is usually made by the following reaction: Zn(s) + 2 HCl(aq) → H2(g) + ZnCl2(aq) How many liters

IrinaK [193]

Answer: The volume of hydrogen gas collected over water is 2.13 L

Explanation:

To calculate the number of moles, we use the equation:

$\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}$

Given mass of zinc = 5.566 g

Molar mass of zinc = 65.4 g/mol

Putting values in above equation, we get:

$\text{Moles of zinc}=\frac{5.566g}{65.4g/mol}=0.0851mol$

For the given chemical reaction:

$Zn(s)+2HCl(aq.)\rightarrow H_2(g)+ZnCl_2(aq.)$

As, HCl is present in excess. So, it is considered as an excess reagent.

Zinc is considered as a limiting reagent because it limits the formation of product.

By Stoichiometry of the reaction:

1 mole of zinc produces 1 mole of hydrogen gas.

So, 0.0851 moles of zinc will produce = $\frac{1}[1}\times 0.0851=0.0851mol$ of hydrogen gas

To calculate the volume of hydrogen gas, we use ideal gas equation, which is:

PV = nRT

where,

P = Pressure of hydrogen gas = Total atmospheric pressure - vapor pressure of water = (752 - 18.65) mmHg = 733.35 mmHg

V = Volume of the hydrogen gas

n = number of moles of gas = 0.0851 moles

R = Gas constant = $62.3637\text{ L.mmHg }mol^{-1}K^{-1}$

T = Temperature of hydrogen gas = $21^oC=[21+273]K=294K$

Putting values in above equation, we get:

$733.35mmHg\times V=0.0851mol\times 62.3637\text{ L.mmHg }mol^{-1}K^{-1}\times 294K\\\\V=\frac{0.0851\times 62.3637\times 294}{733.35}=2.13L$

Hence, the volume of hydrogen gas collected over water is 2.13 L

5 0

3 years ago

How many grams of sodium fluoride should be added to 300. mL of 0.0310 M of hydrofluoric acid to produce a buffer solution with

Kisachek [45]

Answer : The mass of sodium fluoride added should be 0.105 grams.

Explanation : Given,

The dissociation constant for HF = $K_a=6.8\times 10^{-4}$

Concentration of HF (weak acid)= 0.0310 M

First we have to calculate the value of $pK_a$ .

The expression used for the calculation of $pK_a$ is,

$pK_a=-\log (K_a)$

Now put the value of $K_a$ in this expression, we get:

$pK_a=-\log (6.8\times 10^{-4})$

$pK_a=4-\log (6.8)$

$pK_a=3.17$

Now we have to calculate the concentration of NaF.

Using Henderson Hesselbach equation :

$pH=pK_a+\log \frac{[Salt]}{[Acid]}$

$pH=pK_a+\log \frac{[NaF]}{[HF]}$

Now put all the given values in this expression, we get:

$2.60=3.17+\log (\frac{[NaF]}{0.0310})$

$[NaF]=0.00834M$

Now we have to calculate the moles of NaF.

$\text{Moles of NaF}=\text{Concentration of NaF}\times \text{Volume of solution}=0.00834M\times 0.300L=0.0025mole$

Now we have to calculate the mass of NaF.

$\text{Mass of }NaF=\text{Moles of }NaF\times \text{Molar mass of }NaF=0.0025mole\times 42g/mole=0.105g$

Therefore, the mass of sodium fluoride added should be 0.105 grams.

4 0

3 years ago