Iodoform test is not given by:

What is formed when oxalic acid is dehydrated with concentrated $H_2SO_4$?

The reagent,from the following,which converts benzoic acid to benzaldehyde in one step is

Oxalic acid when heated with conc. $H_2SO_4$,gives out:

What is formed when ethyl benzoate undergoes saponification with caustic soda?

Oxalic acid reacts with concentrated $H_2SO_4$ to produce a mixture of two gases. When this mixture is passed through caustic potash,one of the gases is absorbed. What substance is formed by the absorption of the gas in caustic potash?