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3 years ago

Why is Darwins theory of evolution by natural selection not just a theory

Chemistry

1 answer:

Mamont248 [21]3 years ago

4 0

Answer:

it talks about reality ..how animals and human came to existence and how they disappear ..this is evolution

the environment chooses those who best fit in it and others are selected ..as in die ..this is referred to as natural selection

and further in this theory .animals produce off springs who survive in the environment

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Suppose you wish to separate a mixture of fine particles of gold and sand, neither of which is soluble in water. if you add liqu

Greeley [361]

The mixture can be separated as shown in the flow chart

4 0

3 years ago

The frequency factors for these two reactions are very close to each other in value. Assuming that they are the same, compute th

MrRissso [65]

The question is incomplete, complete question is :

The frequency factors for these two reactions are very close to each other in value. Assuming that they are the same, compute the ratio of the reaction rate constants for these two reactions at 25°C.

$\frac{K_1}{K_2}=?$

Activation energy of the reaction 1 , $Ea_1$ = 14.0 kJ/mol

Activation energy of the reaction 2, $Ea_1$ = 11.9 kJ/mol

Answer:

0.4284 is the ratio of the rate constants.

Explanation:

According to the Arrhenius equation,

$K=A\times e^{\frac{-Ea}{RT}}$

The expression used with catalyst and without catalyst is,

$\frac{K_2}{K_1}=\frac{A\times e^{\frac{-Ea_2}{RT}}}{A\times e^{\frac{-Ea_1}{RT}}}$

$\frac{K_2}{K_1}=e^{\frac{Ea_1-Ea_2}{RT}}$

where,

$K_2$ = rate constant reaction -1

$K_1$ = rate constant reaction -2

Activation energy of the reaction 1 , $Ea_1$ = 14.0 kJ/mol = 14,000 J

Activation energy of the reaction 2, $Ea_1$ = 11.9 kJ/mol = 11,900 J

R = gas constant = 8.314 J/ mol K

T = temperature = $25^oC=273+25=298 K$

Now put all the given values in this formula, we get

$\frac{K_1}{K_2}=e^{\frac{11,900- 14,000Jl}{8.314 J/mol K\times 298 K}}=2.3340$

0.4284 is the ratio of the rate constants.

7 0

3 years ago

How many electrons are transferred when magnesium bonds ionically with oxygen

andrew11 [14]

Answer:

2 electrons from magnesium (Mg) is transferred to oxygen (O2) to form Mg2+ and O2-

which combines by strong electrostatic force to form MgO

the equation is

2Mg + O2 -> 2MgO

6 0

3 years ago

Which of the following atoms forms an ionic bond with a sulfur atom? (Points : 3)

elena-s [515]

Ionic bonds are formed when there is complete transfer of valence electrons between two atoms.

Electronegativity tells the trend of an atom to atract electrons.

You should search for the complete set of rules that indicate whether an ionic or covalent bond happens.

There are two relevant rules to state if whether an ionic bond will happen:

- When the difference of electronegativities between the two atoms is greater than 2.0, then the bond is ionic.

- When the difference is between 1.6 and 2.0, the bond is ionic if one of the elements is a metal.

You need to list the electronegativities of the five elements (there are tables with this information)

Element electronegativity

Cu: 1.9
H: 2.2
Cl 3.16
I: 2.66
S: 2.58

Differences:

Cu / S: 2.58 - 1.9 = 0.68
H / S: 2.58 - 2.2 = 0.38
Cl / S: 3.16 - 2.58 =0.58
I / S: 2.66 - 2.58 = 0.08

Those differences are too low to consider that the bond is ionic.

Then the answer is that none of those atoms forms an ionic bond with sulfur.

8 0

3 years ago

Read 2 more answers

When water is heated in an ocean the liquid water changes from and turns into?

sasho [114]

Hello!

The answer is Evaporation

When you add heat to water, it boils, releasing gas into the air. This is called Evaporation. The water changes from a liquid to a gas.

Hope this helped!

6 0

3 years ago