In which of the following production processes is limestone $(CaCO_3)$ $NOT$ used?

In which of the following is the sporophyte parasitic on the gametophyte?

$A$ diverging lens with a focal length of magnitude $25 \, cm$ is placed at a distance of $15 \, cm$ from a converging lens with a focal length of magnitude $20 \, cm$. $A$ beam of parallel light falls on the diverging lens. The final image formed is:

If $u+iv = \frac{3i}{x+iy+2}$,then $y=$

Energy required to remove an electron from an aluminium surface is $4.2 \text{ eV}$. If light of wavelength $2000 \text{ \AA}$ falls on the surface, the velocity of the fastest electron ejected from the surface will be:

The distance between two coherent sources is $0.1 \, mm$. The fringe-width on a screen $1.2 \, m$ away from the source is $6.0 \, mm$. The wavelength of light used is $\dots \, \mathring{A}$.