Which of the following allotropes of carbon is isomorphous with crystalline silicon?

Phosphorus has the oxidation state of $+3$ in

Which one of the following statements about the zeolites is false?

Which of the following is true for diamond?

On heating copper nitrate strongly,$.......$ is finally obtained.

Which of the following statements are correct?
$i$. The basic structural unit of silicates is $SiO_4^{4-}$
$ii$. Silicones are biocompatible
$iii$. Producer gas contains $CO$ and $N_2$
The correct option is