The correct order of reactivity for reactions involving the cleavage of the $C-X$ bond in the following compounds is:

The magnetic field due to a straight conductor of uniform cross section of radius $a$ and carrying a steady current is represented by

The reading of the ammeter in the circuit shown will be: (in $A$)

Liquids $A$ and $B$ form an ideal solution. If $X_A$ and $Y_A$ are the mole fractions of $A$ in the solution and in vapour phase in equilibrium,respectively,then (Given $P_A^o > P_B^o$):

Two particles $A$ and $B$ move with constant velocities $\vec{v}_1$ and $\vec{v}_2$. At the initial moment,their position vectors are $\vec{r}_1$ and $\vec{r}_2$ respectively. The condition for their collision is

The mutual inductance of a pair of coils,each of $N$ turns,is $M$ henry. If a current of $I$ ampere in one of the coils is brought to zero in $t$ seconds,the $emf$ induced per turn in the other coil,in volts,will be