Diborane reacts with $HCl$ in the presence of $AlCl_3$ and liberates

The input resistance of a common emitter transistor amplifier,if the output resistance is $500 \, k\Omega$,the current gain $\alpha = 0.98$ and power gain is $6.0625 \times 10^6$,is....$\Omega$

The ratio of the magnetic field at the centre of a current-carrying circular wire and the magnetic field at the centre of a square coil made from the same length of wire will be

$\frac{12}{3 + \sqrt{5} - 2\sqrt{2}} = $

An $X$-ray tube is operated at $50 \ kV$. The minimum wavelength produced is ..... $\mathring{A}$.

In $NaCl$ the centres of two nearest like-charged ions are present at a distance of