Calculate rate constant of a first order reaction having pre exponential factor $1.6 \times 10^{13} \mathrm{~s}^{-1}$.

$$ \left(\mathrm{E}_{\mathrm{a}} / 2.303 \mathrm{RT}=21\right) $$

What is the difference in molar mass of Undecane and Dodecane?

Which cation from following exhibits no magnetic moment?

Identify the product when chlorobenzene is heated with nitrating mixture.