Glycerol is_____________.

Which among the following statements is correct? (i) Glycerol on reaction with oxalic acid at 110°C (383 K) and followed by heating and hydrolysis gives formic acid and glycerol. (ii) Glycerol on reaction withoxalic acid at 230°C (503 K) and followed by heating gives allyl alcohol. (iii) Glycerol on oxidation with dil. HNO_3 gives a mixture of glyceric and tartronic acid, (iv) Glycerol on oxidation with conc. HNO_3 gives glyceric acid.