supergiants is one of the massive and most luminous star that has a visual magnitudes between about −3 and −8, the temperature range from about 3,400 K to over 20,000 K. its element are different from less luminous stars. It shows helium and nitrogen at the surface due to convection of these fusion products to the surface, helium is also formed in the core and shell by fusing hydrogen and nitrogen. They contain carbon-13, lithium and s-process elements and also enriched with oxygen.
This is True . the reabsorption through the proximal tubule is obligatory 80% whereas water reabsorption through distal tubule is facultative but mostly through collector tubules 15 % ( under the action of aldosteron and antidiuretic hormone).
