Answer:
C
Explanation:
Control over nitrogenase activity is accomplished by NH4+ prevents expression of the genes that encode nitrogenas.
Nitrogenase synthesis in free-living N2-fixing bacteria is universally under repressor control by ammonia. This, however, is not
the case for rhizobia. A need for N2 as inducer apparently does not
exist. The degree of ammonia repression is unusual in its strength.
Nitrogenase activity is at least 1O,OOO-fold lower in extracts of
NH4+-grown cells versus N2-grown cells.
The answer is A.18 let me know if you want an explanation
Cassini was the fourth space probe to visit Saturn and the first to enter its orbit.
To the eye – taken by itself – Alpha Centauri A appears as the fourth-brightest star seen from Earth, just slightly outshone by Arcturus. However, the combined light of Alpha Centauri A and B is slightly greater than Arcturus, so in that sense it appears as the third-brightest star visible in Earth's sky.
Answer: I2 is the Oxidant; while the 2S2O3(-2) is the reductant.
Explanation:
An Oxidant is any substance that oxidizes, or receives electrons from, another; in so doing, it becomes reduced in oxidation number.
A Reductant thus exactly the opposite.
Note that the equation provided shows that Iodine (I2) received an electron to become NEGATIVELY CHARGED:
I2 --> 2I-.
The oxidation number reduced from 0 to -1.
In contrast, the oxidation number of 2S2O3(-2) increases from -4 to -2.
Thus, I2 is the Oxidant; while the 2S2O3(-2) is the reductant.
