Which part of the human ear plays no role in hearing as such but is otherwise very much required?

The tyre of a motor car contains air at $15^{\circ} C$. If the temperature increases to $35^{\circ} C$,the approximate percentage increase in pressure is (ignore the expansion of the tyre).

If the angular velocity of a disc depends on the angle rotated $\theta$ as $\omega = \theta^2 + 2\theta$,then its angular acceleration $\alpha$ at $\theta = 1 \ rad$ is ......... $rad/sec^2$.

An oil drop having a mass $4.8 \times 10^{-13} ~kg$ and charge $2.4 \times 10^{-18} ~C$ stands still between two charged horizontal plates separated by a distance of $1 ~cm$. If now the polarity of the plates is changed,the instantaneous acceleration of the drop is: $(g = 10 ~ms^{-2})$ (in $~ms^{-2}$)

$\frac{d}{dx}[(1 + x^2)\tan^{-1}x] = $

If one of the lines of the pair of straight lines $ax^2 + 2hxy + by^2 = 0$ bisects the angle between the coordinate axes,then: