The figure shows wave fronts in still water,moving in the direction of the arrow towards the interface $PQ$ between a shallow region and a deep (denser) region. Which of the lines shown may represent one of the wave fronts in the deep region?

If $\lim _{x \rightarrow 0}\left(\frac{\cos 4 x+a \cos 2 x+b}{x^4}\right)$ is finite,then the values of $a, b$ are respectively :

Explain the following term with an example: Tridentate ligands.

$A$ uniform magnetic field $B$ exists in a cylindrical region of radius $10\, cm$ as shown in the figure. $A$ uniform wire of length $80\, cm$ and resistance $4.0\,\Omega$ is bent into a square frame and is placed with one side along a diameter of the cylindrical region. If the magnetic field increases at a constant rate of $0.010\, T/s$,find the current induced in the frame.

Which fungus has proven to be an effective biological control agent?

We have two spheres,one of which is a hollow shell and the other is solid. They have identical masses and moments of inertia about their respective diameters. The ratio of their radii is given by