The depression in freezing point observed for a formic acid solution of concentration 0.5 mL L^-1 is $0.0405°C.$ Density of formic acid is 1.05 g mL^-1. The Van't Hoff factor of the formic acid solution is nearly: (Given for water $K_f=1.86kkgmo{l}^{-1}$ )

At 25°C the standard emf of cell having reactions involving two electrons change is found to be 0.295 V. The equilibrium constant of the reaction is :

Kindly consider the following 

Which of the following will not give ether as product :-

Which is most reactive towards electrophilic aromatic substitution reaction :-

Which one of the following ions is the most stable in aqueous solution ?

(At. No. Ti = 22, V = 23, Cr = 24, Mn=25)