According to Graham's law,the rate of diffusion of $CO$,$O_2$,$N_2$,and $CO_2$ follows the order:

Two non-reactive monoatomic ideal gases have their atomic masses in the ratio $2 : 3$. The ratio of their partial pressures,when enclosed in a vessel kept at a constant temperature,is $4 : 3$. The ratio of their densities is :-

There is a small hole in a hollow sphere. Water enters it when it is taken to a depth of $40 \, cm$ under water. The surface tension of water is $0.07 \, N/m$. The diameter of the hole is ...... $mm$.

$A$ Van de Graaff generator has a spherical metal shell as an electrode which is at a potential $15 \times 10^6 \ V$. If the dielectric strength of the surrounding medium is $5 \times 10^7 \ V \ m^{-1}$,then the diameter of the shell is: (in $cm$)

An object $2.4 \, m$ in front of a lens forms a sharp image on a film $12 \, cm$ behind the lens. $A$ glass plate $1 \, cm$ thick,of refractive index $1.50$,is interposed between the lens and the film with its plane faces parallel to the film. At what distance (from the lens) should the object be shifted to be in sharp focus on the film? (in $m$)

$\left(\frac{1+i}{1-i}\right)^4+\left(\frac{1-i}{1+i}\right)^4$ is equal to