The number of circles that touch all the three lines $x+y-1=0$,$x-y-1=0$,and $y+1=0$ is

The coil in a moving coil galvanometer experiences a torque proportional to the current passing through it. If a steady current $i$ is passed through it,the steady deflection of the coil is found to be $90^o$. Now,the steady current is switched off and a charge $q$ is suddenly passed through the coil. If the coil has $N$ turns of area $A$ and its moment of inertia is $I$ about the axis of rotation,then the maximum angle through which it deflects upon passing charge $q$ is:

If $\tan A + \cot A = 4,$ then $\tan^4 A + \cot^4 A$ is equal to

The basis of the quantum mechanical model of an atom is

$\begin{aligned} & \frac{x^2+x+1}{(x-1)(x-2)(x-3)}=\frac{A}{x-1}+\frac{B}{x-2}+\frac{C}{x-3} \\ & \Rightarrow A+C= \end{aligned}$

Milk is an example of