The simplest and most primitive embryophytes are ......

Which of the following elements does not show variable valency?

Which one of the following precedes the re-formation of the nuclear envelope during the $M$ phase of the cell cycle?

Which of the following is a heterosporous pteridophyte?

In plants,which elements are most readily mobilized?

In the electric network shown,when no current flows through the $4 \Omega$ resistor in the arm $EB$,the potential difference between the points $A$ and $D$ will be $.............\,V$.