Which of the following is a synthetic auxin?

In which of the following compounds is the ratio of the size of the anion to the size of the cation the smallest?

$A$ double convex lens,made of a material of refractive index $\mu_1$,is placed inside two liquids of refractive indices $\mu_2$ and $\mu_3$,as shown. Given $\mu_2 > \mu_1 > \mu_3$. $A$ wide,parallel beam of light is incident on the lens from the left. The lens will give rise to

What is the atomic number of the element with the maximum number of unpaired $4p$ electrons?

$A$ constant voltage of $25 ~V$ is applied to a series $L-R$ circuit at $t=0$,by closing a switch. What is the potential difference across the resistor and the inductor at time $t=0$?

Light of wavelength $2475 \, Å$ is incident on barium. Photoelectrons emitted describe a circle of radius $100 \, cm$ in a magnetic field of flux density $\frac{1}{\sqrt{17}} \times 10^{-5} \, T$. The work function of the barium is ............. $eV$ (given $\frac{e}{m} = 1.7 \times 10^{11} \, C/kg$).