In contrast to annelids,the Platyhelminthes show:

The shadow of a tower standing on a level ground is found to be $60 \, m$ longer when the sun's altitude is $30^\circ$ than when it is $45^\circ$. The height of the tower is

$A$ body of mass $1\,kg$ crosses a point $O$ with a velocity $60\,ms^{-1}.$ $A$ force of $10\,N$ directed towards $O$ begins to act on it. It will again cross $O$ in ........ $\sec$.

Select the correct pair from the following.

$A$ uniform rod of mass $M$ and length $L$ is placed on a smooth horizontal surface. $A$ horizontal force $F$ is applied at one end of the rod perpendicular to its length. The acceleration of the centre of mass of the rod is:

When a non-volatile solute is added to a solvent,the vapor pressure decreases by $10 \ mm$. The mole fraction of the solute is $0.2$. If the vapor pressure decreases by $20 \ mm$,what will be the mole fraction of the solvent?