Which of the following is not a biofertilizer?

At what speed should a source of sound move so that a stationary observer finds the apparent frequency equal to half of the original frequency?

The joint equation of the lines passing through the origin and trisecting the first quadrant is . . . . . .

If the terminal speed of a sphere of gold (density $= 19.5 \,kg/m^3$) is $0.2 \,m/s$ in a viscous liquid (density $= 1.5 \,kg/m^3$),find the terminal speed of a sphere of silver (density $= 10.5 \,kg/m^3$) of the same size in the same liquid.

In the isoelectronic species,the ionic radii in $\mathring{A}$ of $N^{3-}$,$O^{2-}$,and $F^{-}$ are respectively given by:

The element used by Rutherford in his famous scattering experiment was