Which of the following statements are correct?
(i) Reabsorption of water occurs passively in the initial segment of nephron.
(ii) Nitrogenous wastes are absorbed by passive transport.
(iii) Conditional reabsorption of Na+ and water takes place in DCT.
(iv) DCT reabsorbs ${\mathrm{H}\mathrm{C}\mathrm{O}}^3$ .
(v) DCT is capable of selective secretion of ${\mathrm{H}}^{+},\mathrm{ }{\mathrm{K}}^{+}$ and ${\mathrm{N}\mathrm{H}}_3$ to maintain pH and ${\mathrm{N}\mathrm{a}}^{+}-{\mathrm{K}}^{+}$ balance in blood.
(vi) Substances like glucose, amino acids, ${\mathrm{N}\mathrm{a}}^{+}$ , etc., in the filtrate are reabsorbed actively.