The common characteristics between tomato and potato will be maximum at the level of their . . . . . . .

For the redox reaction $xP_4 + yHNO_3 \to H_3PO_4 + NO_2 + H_2O$,find the values of $x$ and $y$.

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

$A$ ray of light is incident on an equilateral glass prism placed on a horizontal table. For minimum deviation,which of the following is true?

There is a small hole in a hollow sphere. Water enters it when it is taken to a depth of $40 \,cm$ under water. The surface tension of water is $0.07 \,N/m$. The diameter of the hole is .......... $mm$.

For a perfectly black body,the coefficient of emission (emissivity) is: