posted by mark .
how many moles are present in 25ml of 0.1m of na2co3
I am assuming you intended to write 0.1 M and not 0.1 m. M stands for molarity; m stands for molality. Chemistry is more exact than writing sentences with no cap and formulas with no caps. CO, Co, and co all mean different things. May I suggest you find the caps key on your keyboard and use it.
mols = M x L = ?