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3 years ago

Can somebody plz answer a.b.c (just make it 1 sentence for each)

Chemistry

2 answers:

Maurinko [17]3 years ago

8 0

Answer:

One sentence that can be written for evidence is:

Fossils. Fossils document the existence of now-extinct past species that are related to present-day species.

Eddi Din [679]3 years ago

7 0

Answer:

I think this is your answer. if I am right so.

Please mark me as brainliest. thanks!!

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Both the oxygen you need to breathe and ozone are gases made only of oxygen. So why can't you survive by breathing ozone?

marshall27 [118]

Answer/Explanation: Two atoms of oxygen form the basic oxygen molecule--the oxygen we breathe that is essential to life. The third oxygen atom can detach from the ozone molecule, and re-attach to molecules of other substances, thereby altering their chemical composition.

8 0

2 years ago

2 points

erica [24]

9 grams of hydrogen gas (H2) will SC Johnson need to react in order to make 1 bottle of Windex.

Explanation:

Balance equation for the formation of ammonia from H2 gas.

N2 + 3H2 ⇒ 2 $NH_{3}$

Given

mass of ammonia in 1 bottle of windex = 51 gram

atomic mass of ammonia 17.01 gram/mole

number of moles = $\frac{mass}{atomic mass of 1 mole}$

number of moles = $\frac{51}{17.01}$

= 3 moles of ammonia is formed.

in 1 bottle of windex there are 3 moles of ammonia 0r 51 grams of ammonia.

From the equation it can be found that:

3 moles of hydrogen reacted to form 2 moles of ammonia

so, x moles of hydrogen will react to form 3 moles of ammonia.

$\frac{2}{3}$ = $\frac{3}{x}$

x = 4.5 moles of hydrogen will be required.

to convert moles into gram formula used:

mass = atomic mass x number of moles (atomic mass of H2 is 2grams/mole)

= 2 x 4.5

= 9 grams of hydrogen.

7 0

3 years ago

If aluminum is diffused into a thick slice of silicon with no previous aluminum in it at a temperature of 1100˚C for 8 hours, wh

RideAnS [48]

Answer:

8.354 nanometers

Explanation:

To treat a diffusive process in function of time and distance we need to solve 2nd Ficks Law. This a partial differential equation, with certain condition the solution looks like this:

$\frac{C_{s}-C{x}}{C_{s}-C_{o}}=erf(x/2\sqrt{D*t})$

Where Cs is the concentration in the surface of the solid

Cx is the concentration at certain deep X

Co is the initial concentration of solute in the solid

and erf is the error function

Then we solve right side,

$\frac{C_{s}-C{x}}{C_{s}-C_{o}}=\frac{1018atoms/cm3-1016atoms/cm3}{1018atoms/cm3}=0.001964$

And we need to look up the inverse error function of 0.001964 resulting in: 0.00174055

Then we solve for x:

$x=0.00174055*2*\sqrt{D*t} =0.00174055*2*\sqrt{2*10^{-12}cm^{2}/s*8h*3600s/h}=8.35464*10^{-7}cm$

6 0

3 years ago

How many kj of heat are needed to completely melt 32.3 g of h2o, given that the water is at its melting point? the heat of fusio

timurjin [86]

Answer: fourth option, 10.8 kJ

Explanation:

The heat of fusion, also named latent heat of fusion, is the amount of heat energy required to change the state of a substance from solid to liquid (at constant pressure).

The data of the heat of fusions of the substances are reported in tables and they can be shown either per mole or per gram of substance.

In this case we have that the heat of fusion for water is reported per mole: 6.02 kJ/mole.

The formula to calculate how many kJ of heat (total heat) are needed to completely melt 32.3 g of water, given that the water is at its melting point is:

Heat = number of moles × heat of fusion

The calculations are:

number of moles = mass / molar mass

number of moles = 32.3 g / 18.015 g/mol = 1.79 mol

Heat = 1.79 mol × 6.02 kJ / mol = 10.8 kJ ← answer

5 0

3 years ago

Read 2 more answers

What is the mass, in grams, of a sample of 6.98 × 1024 atoms of magnesium (Mg)?

monitta

N=6.98*10²⁴
Nₐ=6.022*10²³ mol⁻¹

n(Mg)=N/Nₐ

m(Mg)=n(Mg)M(Mg)=M(Mg)N/Nₐ

m(Mg)=24.3g/mol*6.98*10²⁴/(6.022*10²³mol⁻¹)=281.7 g

5 0

3 years ago