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3 years ago

The most dangerous form of skin cancer which is often caused by over exposure to ultraviolet radiation is what?

1 answer:

8 0

UV exposure that leads to sunburn is proven in developing melanoma, the most dangerous of the three most common types of skin cancer.

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What do plants need to live?

zimovet [89]

Sunlight, soil, water, leaves,

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3 years ago

Read 2 more answers

Refer to the graph. the graph shows the progress of digestion as carbohydrates, fats, and proteins pass through the human digest

nika2105 [10]

3 protein may be the answer

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4 years ago

Many double-displacement reactions are enzyme-catalyzed via the "ping pong" mechanism, so called because the reactants appear to

zhenek [66]

Answer:

D. It will decrease by a factor of 4

Explanation:

According to the question , the equation follows :

$A+B\rightarrow C+D$

Rate law : This states the rate of reaction is directly proportional to concentration of reactants with each reactant raised to some power which may or may not be equal to the stoichiometeric coefficient.

$Rate\ \alpha [A]^{a}[B]^{b}$

$r=[A]^{a}[B]^{b}$ .................(1)

STEP": First, find out the power "a" and "b"

a+b = 3 (because it is given that the reaction follow 3rd order-kinetics)

According to question, doubling the concentration of the first reactant causes the rate to increase by a factor of 2 means,

r' = 2r if [A'] = 2[A]

Here [B] is uneffected means [B']=[B]

hence new rate =

$r'=[A']^{a}[B']^{b}$

Put the value of [A'] , [B'] and r' in the above equation:

$2r=[2A]^{a}[B]^{b}$ ...........(2)

Divide equation (1) by (2) we , get

$\frac{2r}{r}=\frac{[2A]^{2}[B]^{b}}{[A]^{a}[B]^{b}}$

$2= 2(\frac{A}{A})^{a}\times (\frac{B}{B})^{b}$

Here A and A cancel each other

B and B cancel each other

We get,

$2= 2^{a}\times 1^{b}$

1^b = 1 ( power of 1 = 1)

$2= 2^{a}$

This is possible only when a = 1

We know that : a + b = 3

1 + b = 3

b =3 -1 = 2

b = 2

Hence the rate law becomes :

$r=[A]^{a}[B]^{b}$

$r=[A]^{1}[B]^{2}$ .............(3)

Look in the question now, it is asked to calculate the concentration of [B],if cut in half

Hence

[B']=1/2[B]

Insert the value of [B'] in equation (3)

$r'=[A]^{1}[B']^{2}$

$r'=[A]^{1}(\frac{1}{2}[B])^{2}$

$r'=\frac{1}{4}[A]^{1}[B]^{2}$ ............(a)

But

$r=[A]^{a}[B]^{b}$ ..............(b)

Compare equation (a) and (b) , we get

new rate r' =

r' = 1/4 r

7 0

3 years ago

How can you tell which ionic compounds will react in an aqueous solution

Darina [25.2K]

1. Determine if the ionic substances can break apart into ions.
- e.g. CaCO3 isn't very soluble, do it can't dissolve and dissociate. If it can't pop apart, no ions.
2. Swap the partners for all the other ions that you can get from step 1. You can skip pairings with the same charge - a + can't get close to another + to react.
3. Use solubility, acid/base, and redox rules to see if anything will happen with the ions in solution.

3 0

3 years ago

A gas that was cooled to 200 Kelvin has a volume of 65.8 L. If its initial volume was 132.4 L, what was its initial temperature?

Mandarinka [93]

Answer:

Initial temperature, T1 = 99.4 Kelvin

Explanation:

Given the following data;

Initial volume, V1 = 65.8 Litres
Final temperature, T2 = 200 Kelvin
Final volume, V2 = 132.4 Litres

To find the initial temperature (T1), we would use Charles' law;

Charles states that when the pressure of an ideal gas is kept constant, the volume of the gas is directly proportional to the absolute temperature of the gas.

Mathematically, Charles' law is given by the formula;

$\frac {V}{T} = K$