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Tanzania [10]
3 years ago
9

How did oxygen come up to make 21% of the earth's present atmosphere?

Chemistry
1 answer:
MakcuM [25]3 years ago
4 0
Tiny organisms known as cyanobacteria, or blue-green algae.
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For which elements are outer electrons and valence electrons the same?
spin [16.1K]

Answer:

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Explanation:

4 0
3 years ago
Someone help me please, I will give you brainliest
Nikitich [7]

Answer:

conserve mass.

Explanation:

3 0
4 years ago
Consider the equilibrium: HCOOH(aq) + F-(aq) <----> HCOO-(aq) + HF (aq) Given that the Ka of HCOOH = 1.8 x 10-4 and the Ka
Aleks [24]

Hey there!:

K = Ka * Kb / Kw

Ka = 1.8*10⁻⁴

Kb = 10⁻¹⁴ / 6.8*10⁻⁴

K =  1.8*10⁻⁴ * ( 10⁻¹⁴/ 6.8*10⁻⁴ ) * ( 1 / 10⁻¹⁴ )

K =  = 1.8 / 6.8

K = 0.265

Answer A

Therefore:

K is less than on the forward reaction is not favorable .


Hope That helps!

8 0
3 years ago
What type of atoms form covalent bonds?
mariarad [96]

Answer: :)

Explanation:

In a covalent bond, the atoms bond by sharing electrons. Covalent bonds usually occur between nonmetals. For example, in water (H2O) each hydrogen (H) and oxygen (O) share a pair of electrons to make a molecule of two hydrogen atoms single bonded to a single oxygen atom

4 0
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An element whose third shell contains two <br> p<br> electrons
pentagon [3]
Maybe sodium? becasue its an element and I would like some points... sorryy:((((
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