Trees and shrubs have . . . . . . in their bark for gaseous exchange.

Calculate the $emf$ of the cell $Cu_{(s)}|Cu^{2+}_{(aq)}||Ag^{+}_{(aq)}|Ag_{(s)}$. Given: $E_{Cu^{2+} / Cu}^0 = +0.34 \ V$,$E_{Ag^{+} / Ag}^0 = 0.80 \ V$.

$A$ particle of mass $4 M$ which is initially at rest explodes into three pieces of masses $M$,$M$ and $2 M$. The equal masses move along $X$ and $Y$-axes with velocities $4 ~ms^{-1}$ and $6 ~ms^{-1}$,respectively. The magnitude of the velocity of the heavier mass is

If $P=(0,1,2)$,$Q=(4,-2,1)$,and $O=(0,0,0)$,then $\angle POQ$ is equal to

$A$ single slit of width $0.20 \, mm$ is illuminated with light of wavelength $500 \, nm$. The observing screen is placed $80 \, cm$ from the slit. The width of the central bright fringe will be.....$mm$

If $A$ and $B$ are two sets,then $A \cap (A \cup B)'$ is equal to