Graphite is used as a dry lubricant because of its

$Si_3O_9^{-6}$ (having three tetrahedral units) is represented as:

With respect to graphite and diamond,which of the statement$(s)$ given below is (are) correct?
$(A)$ Graphite is harder than diamond.
$(B)$ Graphite has higher electrical conductivity than diamond.
$(C)$ Graphite has higher thermal conductivity than diamond.
$(D)$ Graphite has higher $C-C$ bond order than diamond.

Among the following nitrates,Lead nitrate,Silver nitrate,and Ammonium nitrate; the one that decomposes without leaving any solid residue is

For the $14^{th}$ group (carbon family),which of the following statements is correct regarding the properties as the atomic number increases?

Carbon and germanium belong to the $14^{th}$ group. The maximum coordination number of carbon is less than germanium,because of