Well it transports white blood cells to infected areas.
Gradpoint ? And the answer is water.
Answer: Homogenous mixture.
Explanation:
(6) first choice: the frequency appears higher and wavelength is shorter.
The car approaches a stationary observer and so the sound will appear to have shorter wavelength. This creates an effect of its siren to sound with higher frequency than it would do if both were stationary.
(7) The Doppler formula for frequency in the case of a stationary observer and source approaching it is as follows:

The wavelength is then

The third choice "0.80m; 431Hz" is correct
Yes, N2 is a triple bond.
Hope it helps!