$A$ transformer works on the principle of

The function $f(x) = x e^{-x}, \forall x \in R$ attains a maximum value at $x$ equal to

Which one of the following is true for an exothermic reaction $A \rightleftharpoons B$,if $E_f$ and $E_b$ are the activation energies of forward and backward reactions respectively?

If $R$ is an equivalence relation on a set $A$,then $R^{-1}$ is

Consider the following statements $A$ and $B$ and identify the correct answer given below.
$A$. Peltier coefficient is numerically equal to the potential difference across the junctions of the thermocouple through which current is flowing.
$B$. According to Thomson,energy is neither absorbed nor evolved at the junction of a thermocouple but is absorbed or evolved only along the lengths of both the conductors.