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In-s [12.5K]
3 years ago
14

Megan experimented with growing mold. She took 3 pieces of bread from the same loaf and placed each into a plastic sandwich bag.

Before sealing the bag, she added 5 drops of water to each slice. Next, she placed one bag on her window sill, one in a dark cabinet, and one in a room away from sunlight. Megan concluded that the different amount of mold that grew on each slice was due to the amount of light it received. Is this a valid conclusion?
A) Yes, because the light was the manipulated variable.


B) Yes, because the light was the controlled variable.


C) No, because the light could not have affected the growth.


D) No, because the light should have been the same for each bread slice.
Chemistry
2 answers:
kvasek [131]3 years ago
3 0

Answer:

Yes, because the light was the manipulated variable

Explanation:

djyliett [7]3 years ago
3 0

Answer:

Your answer would be A. Yes, because the light was the manipulated variable.

Explanation:

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Estimate the number of moles of water in all the Earth's oceans. Assume water covers 75% of the Earth to an average depth of 3 k
o-na [289]

Answer:

there are approximately n ≈ 10²² moles

Explanation:

Since the radius of the earth is approximately R=6378 km= 6.378*10⁶ m , then the surface S of the earth would be

S= 4*π*R²

since the water covers 75% of the Earth's surface , the surface covered by water Sw is

Sw=0.75*S

the volume for a surface Sw and a depth D= 3 km = 3000 m ( approximating the volume through a rectangular shape) is

V=Sw*D

the mass of water under a volume V , assuming a density ρ= 1000 kg/m³ is

m=ρ*V

the number of moles n of water ( molecular weight M= 18 g/mole = 1.8*10⁻² kg/mole ) for a mass m is

n = m/M

then

n = m/M = ρ*V/M = ρ*Sw*D/M = 0.75*ρ*S*D/M = 3/4*ρ*4*π*R² *D/M = 3*π*ρ*R² *D/M

n=3*π*ρ*R² *D/M

replacing values

n=3*π*ρ*R² *D/M = 3*π*1000 kg/m³*(6.378*10⁶ m)² *3000 m /(1.8*10⁻² kg/mole) = 3*π*6.378*3/1.8 * 10²⁰ = 100.18 * 10²⁰ ≈ 10²² moles

n ≈ 10²² moles

8 0
3 years ago
What is the net ionic equation for ammonia and phosphoric acid?
olganol [36]
 N<span>et ionic equation for ammonia and phosphoric acid</span>  is 
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hope this helps
7 0
3 years ago
The decomposition of nitrogen dioxide is described by the following chemical equation: Suppose a two-step mechanism is proposed
Mandarinka [93]

Answer:

<u>first step </u>

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<u>second step</u>

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Explanation:

<u>first step </u>

NO2(g)  ------------------------------------> NO(g) + O(g)

<u>second step</u>

NO2(g) + O(g) -----------------------------> NO(g) + O2(g)

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Gallionella bacteria can get energy from the reaction fe2+ → fe3+. This reaction is an example of
djverab [1.8K]

The gallionella bacteria  reaction

that is Fe2+ →  Fe3+ is example of  oxidation reaction (answer A)

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