Which one of the following is a correct set?

The gas which turns lime water milky is:

Match the following:
| List-$I$ | List-$II$ |
| :--- | :--- |
| $A$. Carbon black | $I$. Electrodes in batteries |
| $B$. Graphite | $II$. Extraction of metals |
| $C$. Diamond | $III$. Abrasive |
| $D$. Activated charcoal | $IV$. Filler in automobile tyres |
| | $V$. Air conditioning system |

Carbon and silicon belong to group $IV$. The maximum coordination number of carbon in commonly occurring compounds is $4$,whereas that of silicon is $6$. This is due to

Which of the following elements shows a stable $+2$ oxidation state?

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: