How many geometrical isomers are possible for the complex $[Mab(AB)_2]^{\pm n}$?

The reaction of $CH_3-CH=CH-C_6H_4-OH$ with $HBr$ gives:

Which of the following is a polyamide?

$A$ cell of $emf$ $E$ and internal resistance $r$ is connected in series with an external resistance $nr$. Then,the ratio of the terminal potential difference to $emf$ is

The White Revolution is associated with which industry?

$A$ sonometer wire is stretched by hanging a metal bob. The fundamental frequency of vibration of the wire is '$n_1$'. When the bob is completely immersed in water,the frequency of vibration of the wire becomes '$n_2$'. The relative density of the metal of the bob is