Salt (W) gives golden yellow colouration in Bunsen flame. When (W) is oxidised by acidified K_(2)Cr_(2)O_(7), a colourless gas (X) is evolved which turns lime water milky and the milkiness disappears on passing excess of gas (X). However gas (X) does not decolourise pink solution of acidified KMnO_(4). when aqueous solution of salt (W) is added slowly to hydrated MnO_(2), red coloured solution is obtained due to formation of soluble complex (Y) along with evolution of gas (X). Gas (X) is:

Salt (W) gives golden yellow colouration in Bunsen flame. When (W) is

1.	Salt (W) gives golden yellow colouration in Bunsen flame. When (W) is oxidised by acidified K_(2)Cr_(2)O_(7), a colourless gas (X) is evolved which turns lime water milky and the milkiness disappears on passing excess of gas (X). However gas (X) does not decolourise pink solution of acidified KMnO_(4). when aqueous solution of salt (W) is added slowly to hydrated MnO_(2), red coloured solution is obtained due to formation of soluble complex (Y) along with evolution of gas (X). Gas (X) is:
Answer» `CO_(2)` `SO_(2)` `SO_(3)` `NO_(2)` Solution :`underset((w))(Na_(2)C_(2)O_(4))+K_(2)Cr_(2)OP_(7) rarr underset((x))(CO_(2)),` `7C_(2)O_(4)^(2-)+2MnO(OH)_(2)DARR +8H^(+) rarr 2[Mn(C_(2)O_(4))_(3)]^(3-)+2CO_(2)uarr +6H_(2)O`