Consider two reactions:
$I.$ $Zn +$ conc. $HNO_3$ (hot) $\rightarrow Zn(NO_3)_2 + X + H_2O$
$II.$ $Zn +$ dil. $HNO_3$ (cold) $\rightarrow Zn(NO_3)_2 + Y + H_2O$
Compounds $X$ and $Y$ are respectively:

Two point charges $+9e$ and $+e$ are placed at a distance of $16\, cm$ apart. Where should a third charge $q$ be placed between them so that it remains in equilibrium?

If two soap bubbles of different radii are connected by a tube, then

In the figure,the potentiometer wire $AB$ of length $L$ and resistance $9r$ is joined to the cell $D$ of $emf$ $\varepsilon$ and internal resistance $r$. The cell $C$'s $emf$ is $\varepsilon / 2$ and its internal resistance is $2r$. The galvanometer $G$ will show no deflection when the length $AJ$ is

If $\alpha$ and $\beta$ are the roots of $x^2-2x+4=0$,then the value of $\alpha^6+\beta^6$ is

The family of curves in which the sub-tangent at any point to any curve is double the abscissa is given by