During the estimation of oxalic acid against $KMnO_4$,the self-indicator is:

$A$ conducting ring is placed around the core of an electromagnet as shown in the figure. When key $K$ is pressed,the ring

$A$ black body at a temperature of $227^{\circ}C$ radiates heat energy at the rate of $5 \ cal/cm^2-sec$. At a temperature of $727^{\circ}C$,the rate of heat radiated per unit area in $cal/cm^2-sec$ will be:

Select the incorrect statement.

$(p \to q) \leftrightarrow (q \vee \sim p)$ is

The relative reactivities of acyl compounds towards nucleophilic substitution are in the order of