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3 years ago

5

Why is it important to have a control group in a experiment?

2 answers:

goldenfox [79]3 years ago

5 0

You would compare the results from the experimental group with the results of the control group to see what happens when you change the variable you want to examine. A control group is an essential part of an experiment because it allows you to eliminate and isolate these variables.
Hopefully this helped.

zysi [14]3 years ago

4 0

Answer:it allows you to eliminate and isolate variables.

Explanation:

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Answer:

$m=\rho\times \frac{4}{3} \times \pi \times(r_2^3-r_1^3 )$

Explanation:

We have to make a hollow sphere of inner radius $r_1$ and outer radius $r_2$ .

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Therefore the net volume of material required to make the sphere:

$V=V_t-V_h$

$V=\frac{4}{3} \pi(r_2^3-r_1^3)$

Now let the density of the of the material be $\rho$ .

<u>Then the mass of the material used is:</u>

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3 years ago

A sample contains 36 g of a radioactive isotope. How much radioactive isotope remains in the sample after 3 half-lives?

Gre4nikov [31]

Answer:

<u>Option "C":</u> "4.5 g"

Explanation:

N0 = 36 g, Let half-life is T.

t = 3 T, n is number of half lives = t / T = 3

<u>By using the decay law of radioactivity</u>

N / N0 = (1 / 2)^n

where

"N0" be the "initial amount"

"N" be the "amount left"

"n" be the "number of half-lives"

N / 36 = (1/2)^3

N / 36 = 1 / 8

N = 36 / 8 = 4.5 g

3 0

3 years ago

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