The electronic configuration of $Yb^{2+}$ is:

What is the correct order of stability for the superoxides?

Two identical conducting spheres having unequal positive charges $q_1$ and $q_2$ are separated by a distance $r$. If they are made to touch each other and then separated again to the same distance,the electrostatic force between them in this case will be:

The idea of secondary wavelets for the propagation of a wave was first given by

$A$ magnetic needle is kept in a non-uniform magnetic field. It experiences

$A$ line passing through the point of intersection of $x+y=4$ and $x-y=2$ makes an angle $\tan ^{-1}\left(\frac{3}{4}\right)$ with the $x$-axis. It intersects the parabola $y^{2}=4(x-3)$ at points $(x_{1}, y_{1})$ and $(x_{2}, y_{2})$ respectively. Then,$|x_{1}-x_{2}|$ is equal to