Minimum weight of carbon required to prepare `5.6` lit `CO_(2)` at STP is

The P^(H) of a sample of KOH solution is 12.3979 . The weight of solid KOH of 70% pure required to prepare 2.5 lit of this solution is

How much marble of 96.5% purity would be required to prepare 100 litres of carbon dioxide at S.T.P. when marble is acted upon by dil HCl ?

Minimum number of carbon atoms required for an alkane to show any kind of isomerism.