What is the value of $\angle S-S-S$ in the puckered $S_8$ ring of rhombic sulfur (in $^{\circ}$)?

Which of the following hydrides is the least stable?

Assertion : $SiF_6^{2-}$ is known but $SiCl_6^{2-}$ is not.
Reason : Size of fluorine is small and its lone pair of electrons interacts with $d-$orbitals of $Si$ strongly.

In the carbon family,elements other than carbon do not form $p\pi - p\pi$ bonds because their atomic radii are very ........

The sides of a matchbox have a coating of:

Which of the following is true for diamond?