Which of the following is incorrect for physisorption?

The correct order of dipole moment is

Half-life of a radioactive substance $A$ is two times the half-life of another radioactive substance $B$. Initially,the number of nuclei of $A$ and $B$ are $N_A$ and $N_B$ respectively. After three half-lives of $A$,the number of nuclei of both are equal. Then the ratio $\frac{N_A}{N_B}$ is

$A$ plano-convex lens fits exactly into a plano-concave lens. Their plane surfaces are parallel to each other. If the lenses are made of different materials with refractive indices $\mu_1$ and $\mu_2$ and $R$ is the radius of curvature of the curved surface of the lenses,then the focal length of the combination is:

$A$ point object on the principal axis at a distance $15\, cm$ in front of a concave mirror of radius of curvature $20\, cm$ has a velocity of $2\, mm/s$ perpendicular to the principal axis. The velocity of the image at that instant will be.......$mm/s$.

$f(x) = e^x \sin x$, then $f^{(6)}(x)$ is equal to :