4 years ago

How do the independent and dependent variables in an experiment compare?

1 answer:

4 0

An independent variable is the variable that is changed or controlled in a scientific experiment to test the effects on the dependent variable.

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Key words why a rusty nail is chemical

boyakko [2]

Becuase you can't change it back to the shiny nail that it was at first So so therefore its a chemical and chemicals can not be changed back into its regular state.

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3 years ago

How many molecules of oxygen are produced when a sample of 38.9 g of water is decomposed by electricity?

statuscvo [17]

Answer:

A) $6.5\times 10^{23}\ \text{molecules}$

Explanation:

m = Mass of water = 38.9

M = Molar mass of water = 18 g/mol

$N_A$ = Avogadro's number = $6.022\times 10^{23}\ \text{mol}^{-1}$

The reaction of electrolysis would be

$2H_2O(l)\rightarrow 2H_2(g)+O_2(g)$

Number of moles of $H_2O$

$n=\dfrac{m}{M}\\\Rightarrow n=\dfrac{38.9}{18}\ \text{mol}$

From the reaction it can be seen that 2 moles of $H_2O$ gives 1 mole of $O_2$

So, number of moles of $O_2$ produced is

$\dfrac{38.9}{18}\times \dfrac{1}{2}=1.081\ \text{mol}$

Number of molecules

$1.081N_A=1.081\times 6.022\times 10^{23}\\ =6.5\times 10^{23}$

So, $6.5\times 10^{23}\ \text{molecules}$ of oxygen is produced.

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3 years ago

_____ is the state of matter of the sun and stars

Kitty [74]

The answer is C. Gas

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3 years ago

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Will newspaper ink transfer onto slime?

jeka57 [31]

No, unless the slime or paper is wet.

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4 years ago

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Dna contains the template needed to copy itself, but it has no catalytic activity in cells. what catalyzes the formation of phos

Over [174]

I am sure it is DNA polymerase.
I'm a bio major, hope I helped :)

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4 years ago