During the change of $O_2$ to $O_2^-$ ion,the electron adds to which one of the following orbitals?

Sertoli cells are regulated by the pituitary hormone known as:

An inductor and a resistor are connected in series to an $AC$ source of $10 \ V$. If the potential difference across the inductor is $6 \ V$,then the potential difference across the resistor is: (in $V$)

The uncertainties in the velocities of two particles $A$ and $B$ are $0.05 \ m/s$ and $0.02 \ m/s$ respectively. The mass of $B$ is five times that of mass $A$. What is the ratio of uncertainties $\left(\frac{\Delta x_A}{\Delta x_B}\right)$ in their positions?

Which of the following hydrides has the lowest boiling point?

$A$ polygon has $54$ diagonals. Then,the number of its sides is