Which one is used as propellants for rockets?

Which one of the following processes will produce hard water?

One mole of a symmetrical alkene on ozonolysis gives two moles of an aldehyde having a molecular mass of 44 u. The alkene is

On mixing a certain alkane with chlorine and irradiating it with ultraviolet light, it forms only one monochloroalkane. This alkane could be

The oxide that gives H₂O₂ on treatment with dilute acid is 

Trans 2-phenyl-1-bromocyclopentane on reaction with alcoholic KOH produces

A hydrocarbon 'A' on ozonolysis gives two isomeric form 'B' and 'C'. B on oxidation gives 'D'. Silver salt of D contains 59.6% Ag. Structure of hydrocarbon is

Of the five isomeric bexanes, the isomer which can give two monochlorinated compounds is

The electrophile E⁺ attacks the benzene ring to generate the intermediate σ-complex. Of the following, which σ-complex is of lowest energy?

Petrol for aviation purposes must contain