Sulphurous acid is
H2SO4
H2S2O7
H2SO3
HSO4
The sulphur compound used as a food preservative
SO2
SO3
In laboratory preparation of hydrogen, Zinc is treated with the acid
Hydrochloric acid
Sulphuric acid
Nitric acid
Boric acid
Gypsum is
CaSO42H2O
2CaSO4H2O
CaSO4
CaCl2
The acid which removes water from flesh
HCl
HNO3