In which of the following,ortho/para substitution by an electrophile is very facile?

Insects belong to which phylum?

$A$ bob of mass $m$ attached to an inextensible string of length $l$ is suspended from a vertical support. The bob rotates in a horizontal circle with an angular speed $\omega \ rad/s$ about the vertical axis. About the point of suspension:

If the ionic product of water $(K_w)$ is $1.96 \times 10^{-14}$ at $35^{\circ} C$,what is its value at $10^{\circ} C$?

In the reaction of $BaO_2$ with dilute $H_2SO_4$,what are the oxidation states of the most electronegative element in the products?

$\frac{\sqrt{2} \cos 45^{\circ}+\cos 56^{\circ}+\cos 58^{\circ}-\cos 66^{\circ}}{\sqrt{2} \cos 28^{\circ} \cos 29^{\circ} \sin 33^{\circ}} = $