The products formed when heavy water is reacted with magnesium nitride are:

If the radius of a nucleus with mass number $125$ is $1.5 \text{ fermi}$,then the radius of a nucleus with mass number $64$ is: (in $text{ fermi}$)

$A$ double slit experiment is immersed in water of refractive index $1.33$. The slit separation is $1 ~mm$ and the distance between the slit and the screen is $1.33 ~m$. The slits are illuminated by light of wavelength $6300 ~Å$. The fringe width is:

Which of the following is absent in polluted water?

The angle of elevation of the top of the tower observed from each of the three points $A, B, C$ on the ground,forming a triangle,is the same angle $\alpha$. If $R$ is the circum-radius of the triangle $ABC$,then the height of the tower is

If the parametric equations of the circle passing through the points $(3,4), (3,2)$ and $(1,4)$ are $x=a+r \cos \theta$ and $y=b+r \sin \theta$,then find the value of $b^a r^a$.