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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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A 11.97g sample of NaBr contains 22.34 % Na by mass. Considering the law of constant composition (definite proportions), how man
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<h3>Answer:</h3>

2.125 g

<h3>Explanation:</h3>

We have;

  • Mass of NaBr sample is 11.97 g
  • % composition by mass of Na in the sample is 22.34%

We are required to determine the mass of 9.51 g of a NaBr sample.

  • Based on the law of of constant composition, a given sample of a compound will always contain the sample percentage composition of a given element.

In this case,

  • A sample of 11.97 g of NaBr contains 22.34% of Na by mass
  • Therefore;

A sample of 9.51 g of NaBr will also contain 22.345 of Na by mass

  • But;

% composition of an element by mass = (Mass of element ÷ mass of the compound) × 100

  • Therefore;

Mass of the element = (% composition of an element × mass of the compound) ÷ 100

Therefore;

Mass of sodium = (22.34% × 9.51 g) ÷ 100

                         = 2.125 g

Thus, the mass of sodium in 9.51 g of NaBr is 2.125 g

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