How many major groups have recent researchers classified the plant kingdom into?

$A$ conducting ring is placed around the core of an electromagnet as shown in the figure. When key $K$ is pressed,the ring

Four point positive charges of same magnitude $Q$ are placed at four corners of a rigid square frame of side length $L$ as shown in the figure. The plane of the frame is perpendicular to the $Z$-axis. If a negative point charge $-q$ is placed at a distance $z$ away from the centre along the axis $(z << L)$, then:

Which of the following alkali metal ions has the lowest ionic mobility in an aqueous solution?

In male cockroaches,sperms are stored in which part of the reproductive system?

The relative reactivities of acyl compounds towards nucleophilic substitution are in the order of