The de-Broglie wavelength of an electron moving in the $n^{th}$ Bohr orbit of radius 'r' is

The magnetic moment of electron due to orbital motion is proportional to
($n$ = principal quantum number)

A radioactive element has rate of disintegration $16{,}000$ disintegrations per minute at a particular instant. After four minutes, it becomes $2000$ disintegrations per minute. The decay constant per minute is

The Boolean expression for the given combination of logic gates is