Answer:
Option D
Explanation:
The reaction talkes place as follows
Na2C2O4+H2SO4→Na2SO4+H2O
{x} (conc.}
+CO↑+CO2↑
effervescence
Na2C2O4+CaCl2→CaC2O4+2NaCl
{X} white ppt.
5CaC2O4+2KMnO4+8H2SO4→K2SO4+5CaSO4+2MnSO4
purple colourless
+10CO2+8H2O
hence , X is Na2C2O4.