Identify correct statements from the following.
I) Li, Na, K is an example of Dobereiner’s triad
II) According to Newland’s octave theory, Be and Mg will have similar properties
III) Lother meyer plotted graphs between atomic volume vs atomic weight of an element
IV) According to Mosely’s equation, $\sqrt{v}\propto z$

( $v$ = frequency of x-rays characteristic of the metal anticathode)