Decomposition of $H_2O_2$ follows a first order reaction. In fifty minutes the concentration of $H_2O_2$ decreases from $0.5$ to $0.125\;M$ in one such decomposition. When the concentration of $H_2O_2$ reaches $0.05\; M$, the rate of formation of $O_2$ will be :

Question

$\begin{array}{1 1} (1) 6.93 \times 10^{-2} mol\; min^{-1} \\ (2) 6.93 \times 10^{-4} mol \; min^{-1} \\ (3) 2.66 \;L \;min^{-1}\;at\; STP \\ (4) 1.34 \times 10^{-2} mol\; min^{-1} \end{array} $