The first order rate constant for the decomposition of CaCO₃ at 700 K is 6.36 * 10^-3 s^-1 and activation energy is 209 kJ mol^-1.  Its rate constant (in s^-1) at 600K is x * 10^-6. The value of x is_____. (nearest integer).

$\left[GivenR=8.31J{K}^{-1}mo{l}^{-1};log6.36*10^{-3}=-2.19,10^{-4.79}=1.62*10^{-5}\right]$

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)