Which one of the following is the correct relation between frequency f and angular frequency $$\omega$$ ?

A Kelvin thermometer and a Fahrenheit thermometer both give the same regarding for a certain sample. What would be the corresponding reading in a Celsius thermometer?

If the potential difference applied to an X-ray tube is doubled while keeping the separation between the filament and the target as same, what will happen to the cut-off wavelength?

Which one of the following statements is true for the relation, $$F = {{G{m_1}{m_2}} \over {{r^2}}}$$ ? (All symbols have their usual meanings.)