Which of the following is true for diamond?

Which of the following hydrides is the least stable?

Which element does not show catenation property?

The formation of $Al_2O_3$ involves the evolution of a large quantity of heat,which makes its use in:

What would be the major product of the following reaction: $SiCl_4 \xrightarrow{\text{Excess of } H_2O}$?

Assertion $(A)$: The maximum covalency of $Si$ and $Ge$ is $6$ but that of carbon is $4$.
Reason $(R)$: Due to the presence of $d$-orbitals in $Si$ and $Ge$,both these elements can undergo $sp^3d^2$ hybridisation and covalency of $6$ is possible. Carbon has no $d$-orbitals in it and hence its covalency is $4$.
The correct answer is: