If the outer surface of the shell is earthed, then identify the correct statement(s)

${R_1} = 1\,\Omega $ $C_1 \,= 2\,\mu F$
${R_2} = 2\,\Omega $ $C_2 \,= 4\,\mu F$
The time constants ( in $\mu\, s$) for the circuits $I, II, III$ are respectively

(Assume, $\frac{1}{4 \pi \varepsilon_0}=9 \times 10^{+9}\; Nm ^2 C ^{-2}$)
$V$. Energy stored in the above combination is $\mathrm{E}$. When these capacitors are connected in series to the same supply, the stored energy is $\frac{9}{\mathrm{x}} \mathrm{E}$. The value of $x$ is___________.
