The richest sources of vitamin $B_{12}$ are

$A$ proton, when accelerated through a potential difference of $V$, has a de-Broglie wavelength $\lambda$ associated with it. If an $\alpha$-particle is to have the same de-Broglie wavelength $\lambda$, it must be accelerated through a potential difference of:

$\lim _{x \rightarrow 0} x^2 \sin \left(\frac{\pi}{x}\right)$ is equal to

$A$ weightless thread can bear a tension up to $3.7\,kg-wt$. $A$ stone of mass $500\,g$ is tied to it and revolved in a circular path of radius $4\,m$ in a vertical plane. If $g = 10\,ms^{-2}$,then the maximum angular velocity of the stone will be ......... $rad\,s^{-1}$

The joint equation of the lines passing through the origin and trisecting the first quadrant is . . . . . .

The equivalent weight of $H_3PO_4$ in the following reaction is:
$H_3PO_4 + Ca(OH)_2 \to CaHPO_4 + 2H_2O$