The number of six-membered and five-membered rings in Buckminster fullerene respectively is

Thermodynamically most stable allotrope of carbon is

Which of the following halides cannot be hydrolysed?

In the following reaction,assign the correct category for the underlined atom in the product of complete hydrolysis at $R.T.$:
$H_3\underset{-}{P}O_5 + H_2O \longrightarrow H_3PO_4 + H_2O_2$

Which one of the following is a good conductor of electricity?

$A$ major constituent of Portland cement,except lime,is: