Chloroplatinic acid is

An open vessel at $300 \ K$ is heated until $2/5$ of the air in it has been expelled. Assuming the volume of the vessel remains constant,find the temperature to which the vessel has been heated in $K$.

When radiation of the wavelength $\lambda$ is incident on a metallic surface,the stopping potential is $4.8 \ V$. If the same surface is illuminated with radiation of double the wavelength,then the stopping potential becomes $1.6 \ V$. Then,the threshold wavelength for the surface is:

Which of the following factors does $NOT$ favor the formation of an electrovalent (ionic) bond?

If the direction cosines of two lines are given by $l+m+n=0$ and $l^2-5m^2+n^2=0$,then the angle between them is

$A$ linear charge having linear charge density $\lambda$ penetrates a cube diagonally and then it penetrates a sphere diametrically as shown. What will be the ratio of flux coming out of the cube and the sphere?