The catenation tendency of $C, Si$ and $Ge$ is in the order $Ge < Si < C$. The bond energies (in $kJ \ mol^{-1}$) of $C-C, Si-Si$ and $Ge-Ge$ bonds are respectively:

$Ge(II)$ compounds are strong reducing agents,whereas $Pb(IV)$ compounds are strong oxidizing agents. This is due to:

The number of ionisable hydrogens present in the product obtained from a reaction of phosphorus trichloride $(PCl_3)$ and phosphonic acid $(H_3PO_3)$ is

The catenation tendency of $C$,$Si$ and $Ge$ is in the order $Ge < Si < C$. The bond energies (in $kJ \ mol^{-1}$) of $C-C$,$Si-Si$ and $Ge-Ge$ bonds,respectively,are:

$A$ red solid is insoluble in water,but it becomes soluble if a small amount of $KI$ is added to the water. If this red solid is heated in a test tube,it produces a violet-colored vapor and some metallic droplets are observed on the cooler parts of the test tube. This red solid is........

Which non-metals have high melting and boiling points? State them.