Which of the following pairs is incorrectly matched?

The plates of a parallel plate capacitor are charged up to $100 \, V$. $A$ $2 \, mm$ thick plate is inserted between the plates. To maintain the same potential difference,the distance between the capacitor plates is increased by $1.6 \, mm$. The dielectric constant of the plate is:

In an $LC$ circuit,the capacitor has a maximum charge $q_0$. The value of $\left. \frac{di}{dt} \right|_{\max }$ is:

The reaction of ethyl methyl ketone with $Cl_2$ in the presence of excess $OH^-$ gives the following major product:

Which of the following metals is a water pollutant and causes sterility in human beings?

Two cells $A$ and $B$ are connected in the secondary circuit of a potentiometer one at a time,and the balancing lengths are $400 \ cm$ and $440 \ cm$ respectively. The emf of cell $A$ is $1.08 \ V$. The emf of the second cell $B$ in volts is: