A bacterial culture is being tested for its ability to reduce nitrate. After incubation and growth of the bacteria in nitrate broth, there is no accumulation of gas in the Durham tube. The test for the presence of nitrite is colorless. When zinc powder is added, a bright red color develops. Interpret these results.

All this combination of reactions is summarized in that the bacteria reduced nitrate, that is, they added protons to said compound, giving nitrite as a product.

By promoting the appearance of nitrite and that it increases in its concentrations when the zinc dust is thrown away, it becomes reddish since there was a change in pH, that is, the medium was acidified.

Explanation:

Some bacteria take nitrate as a source and end up generating an oxide reduction reaction that gives nitrite as a product, if this reaction advances in a chain, that is, the nitrite is reduced after the nitrate, the product in the future would be ammonia

d concave shape of wave rock

explanation:

the concave shape of wave rock is a very good evidence that supports the evolution of earth due to chemical weathering. if we talk about structure of   wave rock, studies have estimated that it is around 2.7 billion years old. it also serves as the foundation of evidence that it was the place where australian continent began to form.

how the structure of wave rock was created?

studies suggest that structure of wave rock was created when the surrounded area was started to weather due to which deposition of material started on the part of land which now contains wave rock.

the structure of wave rock is considered to be one of the best-known landforms in australia. at the height of around 15 cm, there can be found flared slopes which formulate the margins of hyden rock. it is now assumed by geologists that wave rock was created by subsurface water-induced weathering and not by glaciers, waves or wind.

due to deposition of material over the period of long time, the wave rock became tougher and tougher due to weathering from surrounding terrain. this makes it a physical evidence that supports   the evolution of earth due to chemical weathering.

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explanation:

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