Which of the following species does not exist?

What is aluminosilicate? Which ions are used to balance its electric charge?

What are the $C-C$ single bond length and double bond length in fullerene?

In the following reaction,assign the correct category for the underlined atom based on the product of complete hydrolysis at $R.T.$:
$\underline{Si}F_4 + 2H_2O \longrightarrow H_4SiO_4 + 4HF$

$A$ 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:

Give uses of carbon dioxide.