Which best describes the relationship between the terms frequency, wavelength, and hertz?

Iknow #2 is d. i just need to know why

What are transitions between a liquid and gas called? identify which way they are transitioning

1) which of the following is the best example of a physical change? a) sugar dissolving in tea b) firefly glowing 2) in the combustion of ethane, what is/are the reactants? c2h6 + o2 ==> co2 + h2o a) c2h6 and o2 b) co2 and c2h6