Diamond and emerald are forms of which of the following respectively?

Which of the following species does not exist?

Pick out the correct statement.

The three elements $X$,$Y$ and $Z$ with electronic configurations shown below all form hydrides:

Element	Electronic configuration
$X$	$1s^2, 2s^2, 2p^2$
$Y$	$1s^2, 2s^2, 2p^6, 3s^1$
$Z$	$1s^2, 2s^2, 2p^6, 3s^2, 3p^6, 3d^{10}, 4s^2, 4p^5$

Which set of properties match correctly with properties of the hydrides of these elements?

Which of the following is a suboxide?

The presence of $Si$ in steel gives it