If a vector has 0 magnitude then is it meaningfull to call it vector?

In a classical model of the hydrogen atom, the electron moves around the proton in a circular orbit of radius 0.053 nm. what is the electron's orbital frequency? what is the effective current of the electron?

Examples of states of consciousness include a. daydreaming b. dreaming during sleep c. hypnosis d. all of the above

You are doing a science experiment with a fahrenheit thermometer. your data must be in degrees celsius. if you measure a temperature of 125°f, what is this temperature in degrees celsius