Question on the sodium potassium pump

Not really, osmoregulation is mostly influenced by the kidneys (ADH->water reabsorption from glomerular filtrate). The sodium potassium pump maintains the cell membrane potential (resting potential), and facilitates the transport of substances (e.g. cotransporter protein in the kidney utilises the sodium gradient to transport glucose and amino acids into the cell), etc.

You're talking on a cellular level, when you specify "in an animal" osmoregulation would refer mainly to your kidneys. Yes, for individual cells the Na+/K+ pump is important for osmolarity - but there are hundreds of different osmoregulation mechanisms, none of which have as large an impact as your excretory system.

You could talk about maintaining a resting potential across axon membranes.

yeah, but in an exam i wrote "maintain osmotic balance in animals", do u reckon i would get the mark?

Only if the examiner was feeling particularly generous, I think. As stated, that's majorly covered by other larger processes.

okay thanks.if u dont mind me asking, do u reckon i'd get the marks for these questions:
"state the class of amino acid to which valine belongs" i said non-polar.
"state what causes central diabetes inspidus" i said unable to produce ADH
"state the process by which a response within the cell is triggered by the binding of ADH to the receptor" i said signal transduction cascade

Valine is definitely non polar, so if yourexam board allows polar/non polar as a classification then it's correct.

However, i didn't do much on ADH so i couldn't tell you if those are correct.