The value of ........ is less for D₂O compared to that of H₂O.

All physical constants OF: D2O > H2O
Reason: Physical properties  $\mathrm{\alpha }$ Molecular mass
Exception: Dielectric costant: H2O > D2O
Dielectric constant is a measure of ionisation of a Salt  by the solvent example: 

→Density:${\mathrm{D}}_2\mathrm{O}>{\mathrm{H}}_2\mathrm{O}$
→Boiling point D2O > H2O
→ Latent heat of vapoursation : D2O > H2O
→ Dielectric constant : ${\mathrm{H}}_2\mathrm{O}>{\mathrm{D}}_2\mathrm{O}$