Which scientists conducted in-depth research in the field of plant classification?

If the mean of the data $7, 8, 9, 7, 8, 7, \lambda, 8$ is $8$,then the variance of this data is

If two identical bar magnets,each of length $l$,pole strength $m$ and magnetic moment $M$ are placed perpendicular to each other with their unlike poles in contact,the magnetic moment of the combination is

Cellular respiration is carried out by

In the $HCl$ molecule,the separation between the nuclei of the two atoms is about $1.27 \ \mathring{A}$. The approximate location of the centre of mass of the molecule from the hydrogen atom is ....... $\ \mathring{A}$. (Assuming the chlorine atom to be about $35.5$ times as massive as the hydrogen atom.)