Which of the following statements is $NOT$ correct for potash alum?

The adsorption isotherm for a gas is given by the relation $x = \frac{ap}{1 + bp}$,where $x$ is moles of gas adsorbed per gram of the adsorbent,$p$ is the pressure of the gas,and $a$ and $b$ are constants. Then $x$:

$A$ metal crystallises in a face-centred cubic $(FCC)$ structure. If the edge length of its unit cell is $a$,the closest approach between two atoms in the metallic crystal will be:

$A$ body of mass $M$ at rest explodes into three pieces,two of which of mass $M/4$ each are thrown off in perpendicular directions with velocities of $3 \ m/s$ and $4 \ m/s$ respectively. The third piece will be thrown off with a velocity of.......... $m/s$.

The mass of the earth is $81$ times that of the moon and the radius of the earth is $3.5$ times that of the moon. The ratio of the escape velocity on the surface of the earth to that on the surface of the moon will be:

If the foci of the ellipse $\frac{x^2}{25}+\frac{y^2}{16}=1$ and the hyperbola $\frac{x^2}{4}-\frac{y^2}{b^2}=1$ coincide,then $b^2$ is equal to