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o-na [289]
3 years ago
12

About three billion years ago, single-celled organisms called cyanobacteria lived in Earth’s oceans. They thrived on the ocean’s

abundance of ___ , which they used during the process of photosynthesis. Much later, this process allowed organisms, such as fish, to survive by extracting dissolved ___ from ocean waters.
a. oxygen
b.carbon dioxide
c. nitrogen
Physics
2 answers:
quester [9]3 years ago
6 0

The first blank is carbon dioxide, second one is oxygen

pickupchik [31]3 years ago
3 0
I think its Oxygen. 
ancient cyanobacteria produced Earth's first oxygen-rich atmosphere, which allowed the eventual rise of eukaryotes. T<span>he chloroplasts of eukaryotic algae and plants are derived from cyanobacteria</span>
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One-half mole of propane combines with 2.5 moles of oxygen to produce_____moles of water and_____moles of carbon dioxide.
Virty [35]

The balanced equation of the combustion of the propane is

C_3H_8+5O_2\rightarrow3CO_2+4H_2O

From the above chemical equation, it is clear that 1 mole of propane requires 5 moles of oxygen to undergo complete combustion as the result of this reaction, 3 moles of carbon-di-oxide and 4 moles of water molecules will be produced.

Therefore one-half mole of propane requires 2.5 moles of oxygen to undergo complete combustion. And in the reaction, 1.5 moles of carbon-di-oxide and 2 moles of water molecules are produced.

Therefore the answer is, 'One-half of propane combines with 2.5 moles of oxygen to produce 2 moles of water and 1.5 moles of carbon dioxide'

7 0
1 year ago
Which of the following statements are true?
Likurg_2 [28]

Answer:

Explanation:

(A) True: It is true.

In junction law, the current entering at a junction is equal to teh current leaving at the junction.

(B) False: It is false.

The kirchhoff's junction law is based on the conservation of charge.

(C) True: It is true.

Energy is used in the circuit.

(D) True: It is true.

It is based on the conservation of charge.

4 0
3 years ago
A man walks 30 m to the west, then 5 m to the east in 45 seconds. What is his average speed?
dsp73

The average speed is  0.55 m/s

<h3>What was his displacement?</h3>

Displacement is defined as the change in position of an object.

Mathematically,

D = Initial value - Final Value

D = 30 - 5 = 25m

Now , We have to find the average velocity,

Average velocity is calculated by the formula V = D/t,

where V equals the average velocity, D equals total displacement and t equals total time.

V = D/t

V = 25 m / 45s

V = 0.55 m/s

So , The average speed is o.55 m/s

learn more about average speed:brainly.com/question/9834403

#SPJ1

5 0
2 years ago
Air resistance is a nonconservative force. It always opposes the motion of an object. An airplane flies from New York to Atlanta
LenKa [72]

Answer:

c) is negative

Explanation:

As we know that work done by a force is the product of force and displacement vector.

W= F.d

F= Force

d= displacement

The work done by friction force always negative because it try to oppose the motion and act opposite to the direction of displacement.So the work done by air resistance is negative.

c) is negative

8 0
4 years ago
Which statement most accurately compares Earth’s crust and Earth’s mantle?
notsponge [240]
The earths crust starts the beginging of growth of land and plants while the earths mantle is deeper and has no life living on top of it
6 0
3 years ago
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