Fog is a colloidal solution of

Which one of the following gives Prussian blue colour?

If $A, B, C, D$ are angles of a cyclic quadrilateral,then $\cos A + \cos B + \cos C + \cos D$ is equal to

The element used by Rutherford in his famous scattering experiment was

At $T \text{ K}$,the ratio of kinetic energies of $4 \text{ g}$ of $H_{2(g)}$ and $8 \text{ g}$ of $O_{2(g)}$ is

$A$ horizontal uniform glass tube of $100 \ cm$ length, sealed at both ends, contains a $10 \ cm$ mercury column in the middle. The initial temperature and pressure of air on either side of the mercury column are $31^{\circ} C$ and $76 \ cm$ of mercury, respectively. If the air column at one end is kept at $0^{\circ} C$ and the other end at $273^{\circ} C$, then the pressure of the air at $0^{\circ} C$ is (in $cm$ of $Hg$):