The basic structural unit of silicates is

$A$ $1 \ L$ flask is full of brown bromine vapour. The intensity of the brown colour of the vapour will not decrease appreciably on adding which of the following to the flask?

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.

The number of $S-S$ bonds in the cyclic trimer of sulfur trioxide is .........

Which of the following is a mixed oxide?

$SnCl_2$ acts as a reducing agent because: