Which of the following can show geometrical isomerism?

Which of the following is a characteristic of a prokaryotic organism?

The compound prepared by a substitution reaction of benzene is

An insect crawls up a hemispherical surface very slowly (see the figure). The coefficient of friction between the insect and the surface is $\mu = 1/3$. If the line joining the centre of the hemispherical surface to the insect makes an angle $\alpha$ with the vertical,the maximum possible value of $\alpha$ is given by

The sum of the fourth powers of the roots of the equation $x^3+x+1=0$ is

In the following compounds,the order of acidity is:
$(I)$ Phenol
$(II)$ $p$-Cresol ($4$-methylphenol)
$(III)$ $m$-Nitrophenol
$(IV)$ $p$-Nitrophenol