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Greeley [361]
3 years ago
14

Early Earth was largely anoxic with very little oxygen present in the atmosphere. However, approximately 2 billion years ago, a

rise in atmospheric oxygen concentration was recorded in the geological record. This event, known as the great oxygenation event (GOE), was caused by small microorganisms (cyanobacteria) that likely carried out the process of ____________________ .
Chemistry
1 answer:
blagie [28]3 years ago
8 0

Answer:

Photosynthesis

Explanation:

Cyanobacteria were the first prokaryotic organisms capable of oxygen-evolving complex. Photosynthesis needs an electron source, in this case water (H2O). By photo-oxidation of the water, oxygen (O2) is released (and hydrogen taken).

This led to the accumulation of oxygen in the atmosphere where it got to similar concentrations as in these days.  

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Balance and find out the coefficients of reactions and products ​
kolezko [41]

Answer:

2, 1, 1, 4.

Explanation:

Hello there!

In this case, for the given chemical reaction:

H_2SO_4+Pb(OH)_4\rightarrow Pb(SO_4)_2+H_2O\\

We can see how there is one SO4 on the left and two on the right, thus, we add a 2 in front of H2SO4:

2H_2SO_4+Pb(OH)_4\rightarrow Pb(SO_4)_2+H_2O\\

Next, since there are 8 atoms of hydrogen on the left and two on the right, we add a 4 in front of H2O to obtain:

2H_2SO_4+Pb(OH)_4\rightarrow Pb(SO_4)_2+4H_2O\\

Which is now balanced so the coefficients 2, 1, 1, 4.

Best regards!

6 0
2 years ago
Give an example that shows energy transfer and another one that shows energy transformation.
solong [7]

Answer:

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Explanation:

5 0
2 years ago
10 divided by 2 im confused
Eddi Din [679]

if your serious about this question then it is 5

4 0
3 years ago
Read 2 more answers
in which of the following is the symbol for the ion and the number of electrons it contains given correctly? *
gregori [183]

Answer:Number of electrons that are present in an atom is determined by the electronic configuration of that atom.

If an ion is carrying a positive charge, it means that the atom has lost electrons and if an ion is carrying a negative charge, it means that the atom has gained electrons.

For the given options:

Option A: The atomic number of hydrogen atom is 1 and the electronic configuration for  ion will be:  

Thus, this atom does not have any electrons.

Option B: The atomic number of bromine atom is 35 and the electronic configuration for  ion will be:  

Thus, this atom has 36 electrons.

Option C: The atomic number of aluminium atom is 13 and the electronic configuration for  ion will be:

Explanation:

3 0
3 years ago
Given these reactions, X ( s ) + 1 2 O 2 ( g ) ⟶ XO ( s ) Δ H = − 668.5 k J / m o l XCO 3 ( s ) ⟶ XO ( s ) + CO 2 ( g ) Δ H = +
qwelly [4]

<u>Answer:</u> The \Delta H^o_{rxn} for the reaction is -1052.8 kJ.

<u>Explanation:</u>

Hess’s law of constant heat summation states that the amount of heat absorbed or evolved in a given chemical equation remains the same whether the process occurs in one step or several steps.

According to this law, the chemical equation is treated as ordinary algebraic expressions and can be added or subtracted to yield the required equation. This means that the enthalpy change of the overall reaction is equal to the sum of the enthalpy changes of the intermediate reactions.

The given chemical reaction follows:

X(s)+\frac{1}{2}O_2(g)+CO_2(g)\rightarrow XCO_3(s)      \Delta H^o_{rxn}=?

The intermediate balanced chemical reaction are:

(1) X(s)+\frac{1}{2}O_2(g)\rightarrow XO(s)    \Delta H_1=-668.5kJ

(2) XCO_3(s)\rightarrow XO(s)+CO_2     \Delta H_2=+384.3kJ

The expression for enthalpy of the reaction follows:

\Delta H^o_{rxn}=[1\times \Delta H_1]+[1\times (-\Delta H_2)]

Putting values in above equation, we get:

\Delta H^o_{rxn}=[(1\times (-668.5))+(1\times (-384.3))=-1052.8kJ

Hence, the \Delta H^o_{rxn} for the reaction is -1052.8 kJ.

7 0
3 years ago
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