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Simora [160]
3 years ago
15

What was the oxygen crisis

Chemistry
1 answer:
salantis [7]3 years ago
8 0
The Great Oxidation Event (GOE), sometimes also called the Great Oxygenation Event, Oxygen Catastrophe, Oxygen Crisis, Oxygen Holocaust,[2] or Oxygen Revolution, was a time period when the Earth's atmosphere and the shallow ocean first experienced a rise in oxygen, approximately 2.4 billion years ago (2.4 Ga) to 2.1–2.0 Ga during the Paleoproterozoic era.[3] Geological, isotopic, and chemical evidence suggests that biologically produced molecular oxygen (dioxygen, O2) started to accumulate in Earth's atmosphere and changed Earth's atmosphere from a weakly reducing atmosphere to an oxidizing atmosphere,[4] causing many existing species on Earth to die out.[5] The cyanobacteria producing the oxygen caused the event which enabled the subsequent development of multicellular forms.
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What properties would you expect for CaO? Select all that apply. It is likely a gas or liquid at room temperature. It is likely
defon

Answer: it is likely soluble in water

It will likely light up a bulb in a conductivity apparatus

It will likely have a high melting point

Explanation:

8 0
4 years ago
Read 2 more answers
Explain the change in mass that occurs when the following substances are separately heated in open crucibles
aleksandrvk [35]

Answer:

your answer is (a) Copper Metal

Explanation:

7 0
3 years ago
For the reaction given below, the frequency factor A is 8.7 1012 s−1 and the activation energy is 63 kJ/mol. NO(g) + O3(g) → NO2
Alex73 [517]

Answer:

K(70°C) = 2213.376 s-1

Explanation:

balanced reaction:

  • NO(g) + O3(g) → NO2(g) + O2(g)

∴ Ea = 63 KJ/mol

∴ A = 8.7 E12 s-1

∴ T = 70°C ≅ 343 K

Arrhenius eq:

  • K(T) = Ae∧(- Ea/RT)

∴ R = 8.314 E-3 KJ/K.mol

⇒ K(70°C) = (8.7 E12 s-1)e∧[-(63)/(8.314 E-3)(343)]

⇒ K(70°C) = (8.7 E12 s-1)*(2.5444 E-10)

⇒ K(70°C) = 2213.376 s-1

6 0
3 years ago
Calculation of ph from hydrogen ion concentration what is the ph of a solution that has an h1 concentration of (a) 1.75 3 1025 m
faltersainse [42]
<h2>Solutions:</h2>

<u>Case a:</u> Finding pH for [H⁺] = 1.75 × 10⁻⁵ mol/L :

As we know pH is given as,

                                  pH  = -log [H⁺]

Putting value,

                                  pH  = -log [1.75 x 10⁻⁵]

                                 pH =  4.75

<u>Case b:</u> Finding pH for [H⁺] = 6.50 × 10⁻¹⁰ mol/L :

As we know pH is given as,

                                  pH  = -log [H⁺]

Putting value,

                                  pH  = -log [6.50 × 10⁻¹⁰]

                                 pH =  9.18

<u>Case c:</u> Finding pH for [H⁺] = 1.0 × 10⁻⁴ mol/L :

As we know pH is given as,

                                  pH  = -log [H⁺]

Putting value,

                                  pH  = -log [1.0 × 10⁻⁴]

                                 pH =  4

<u>Case d:</u> Finding pH for [H⁺] = 1.50 × 10⁻⁵ mol/L :

As we know pH is given as,

                                  pH  = -log [H⁺]

Putting value,

                                  pH  = -log [1.50 × 10⁻⁵]

                                 pH =  4.82

7 0
3 years ago
The proton number of barium (Ba) is 56. It is in Group II of the periidic table how many electrons would you expect a barium ato
ella [17]

Answer:

A barium atom would be expected to contain 2 electrons in its outer energy level.

Explanation:

The columns of the periodic table are called groups. There are eighteen groups, numbered from 1 to 18.

The elements of each group have the same number of electrons in their last atomic shell, which is why they have similar chemical properties, because the chemical properties of chemical elements are strongly related to the electrons located in the last atomic shell.

That is, in a group, the chemical properties are very similar, because all the elements of the group have the same number of electrons in their last or last shells.

<u><em>A barium atom would be expected to contain 2 electrons in its outer energy level.</em></u>

7 0
3 years ago
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