The presence of $Si$ in steel gives it

Which of the following salts cannot exist?

Carbon monoxide gas is more dangerous than carbon dioxide gas. Why?

$A$ red solid is insoluble in water. However,it becomes soluble if some $KI$ is added to water. Heating the red solid in a test tube results in the liberation of violet-coloured fumes and droplets of a metal appear on the cooler parts of the test tube. The red solid is:

The stability of dihalides of $Si, Ge, Sn$ and $Pb$ increases in the order:

$SiCl_4$ on hydrolysis forms '$X$' and $HCl$. Compound '$X$' loses water at $1000^{\circ} C$ and gives '$Y$'. Compounds '$X$' and '$Y$' respectively are: