Explain the following observations.

${\mathrm{NH}}_3$ is a stronger base than ${\mathrm{PH}}_3$.

Explain the following observations.

Sulphur has a greater tendency for catenation than oxygen.

Explain the following observations.

Bond dissociation energy of F₂ is less than that of Cl₂.
 

What are the oxidation states of phosphorus in the following compound?

${\mathrm{H}}_3{\mathrm{PO}}_{3 }$

What are the oxidation states of phosphorus in the following compound?

${\mathrm{PCl}}_3$
 

What are the oxidation states of phosphorus in the following compounds?

${\mathrm{Ca}}_3{\mathrm{P}}_2$

What are the oxidation states of phosphorus in the following compounds?

${\mathrm{Na}}_3{\mathrm{PO}}_4$
 

What are the oxidation states of phosphorus in the following compounds?

${\mathrm{POF}}_3$