$Fe$ is made passive by

$A$ parallel plate capacitor of capacitance $C$ is connected to a battery and is charged to a potential difference $V$. Another capacitor of capacitance $2C$ is connected to another battery and is charged to potential difference $2V$. The charging batteries are now disconnected and the capacitors are connected in parallel to each other in such a way that the positive terminal of one is connected to the negative terminal of the other. The final energy of the configuration is

From the ground state electronic configuration of the elements given below,pick the one with the highest value of second ionisation energy.

Which of the following bonds are present in silicones?

The electric field of a plane electromagnetic wave varies with time with an amplitude of $2 \, Vm^{-1}$ propagating along the $z$-axis. The average energy density of the magnetic field (in $J \, m^{-3}$) is:

The mid-point of a chord of the ellipse $x^2+4y^2-2x+20y=0$ is $(2, -4)$. The equation of the chord is