The President is Xi Jinping
Such information is valid when A. it is not biased.
There is no bias in science - the results are either correct or incorrect; personal opinions have nothing to do with that. B is incorrect because the point of experiments is that they can be repeated to achieve the same results. C and D are likewise incorrect as primary sources are important, and you can share the results with others if you want to.
Answer:
1.29649
488.08706 nm

231715700.28346 m/s
Explanation:
n denotes refractive index
1 denotes air
2 denotes solution
= 632.8 nm
From Snell's law we have the relation

Refractive index of the solution is 1.29649
Wavelength is given by

The wavelength of the solution is 488.08706 nm
Frequency is given by

The frequency is 

The speed in the solution is 231715700.28346 m/s