In a container of volume $16.62 \mathrm{~m}^3$ at $0{ }^{\circ} \mathrm{C}$ temperature, 2 moles of oxygen 5 moles of nitrogen and 3 moles of hydrogen are present, then the pressure in the container is

(Universal gas constant $=8.31 \mathrm{~J} \mathrm{~mol}^{-1} \mathrm{~K}^{-1}$ )

If a travelling wave is given by $y(x, t)=0.5 \sin (70.1 x-10 \pi t)$, where $x$ and $y$ are in metre the time $t$ is in second, then the frequency of the wave is

The ratio of the focal lengths of a convex lens when kept in air and when it is immersed in a liquid is $1: 2$. If the refractive index of the material of the lens is 1.5 , then the refractive index of the liquid is

The path difference between two waves given by the equations

$y_1=a_1 \sin \left(\omega t-\frac{2 \pi x}{\lambda}\right)$ and $y_2=a_2 \sin \left(\omega t-\frac{2 \pi x}{\lambda}+\phi\right)$ is