Select the correct order sequence(s).

Ethane contains a carbon-carbon single bond.
Benzene is aromatic in nature. It has resonance. All the carbon-carbon bonds in benzene have a partial double bond character.
Ethylene contains a carbon-carbon double bond.

Acetylene contains a carbon-carbon triple bond.

The order of bond length is, single bond>partial double bond> double bond > triple bond.
${\mathrm{CO}}_3^{2-}$ :-Formation of the gaseous CO₂ is a good indication of carbonate. 

${{\mathrm{CO}}_3}^{2-}+2{\mathrm{H}}^{+}\to {\mathrm{CO}}_2( )+{\mathrm{H}}_2\mathrm{O}$

${\mathrm{PO}}_4^{-3}$ :- Formation of the white precipitate indicates the presence of SO₄^2-.

${\mathrm{Ba}}^{2+}+{\mathrm{SO}}_4^{2-}\to {\mathrm{BaSO}}_4$

Phosphate and carbonate do not react in the presence of HCl.