The correct order of reactivity of hydrogen halides with ethyl alcohol is

The new crop $Triticale$ was developed by intergeneric hybridization between which of the following?

$A$ photon of energy $E$ ejects a photoelectron from a metal surface whose work function is $W_0$. If this electron enters into a uniform magnetic field of induction $B$ in a direction perpendicular to the field and describes a circular path of radius $r$,then the radius $r$ is given by,(in the usual notation)

Nitrobenzene gives $N$-phenylhydroxylamine by

Match the appropriate pairs from List-$I$ and List-$II$ :

List-$I$	List-$II$
$1$. Nitrogen molecules	$(A)$ Continuous spectrum
$2$. Incandescent solids	$(B)$ Absorption spectrum
$3$. Fraunhoffer lines	$(C)$ Band spectrum
$4$. Electric arc between iron rods	$(D)$ Emission spectrum

The intensity of the magnetic induction field at the centre of a single turn circular coil of radius $5 ~cm$ carrying a current of $0.9 ~A$ is: