Gymnosperms lack true fruits because.....

On heating one end of a rod,the temperature of the whole rod will be uniform when

$A$ uniform rod of mass $M$ and length $L$ is placed on a smooth horizontal surface. $A$ particle of mass $m$ moving with velocity $v$ strikes the rod at one end perpendicular to the rod. After the collision,the particle comes to rest. The velocity of the centre of mass of the rod after the collision is:

The area (in square units) of the triangle formed by $x+y+1=0$ and the pair of straight lines $x^2-3xy+2y^2=0$ is

In which of the following organisms is a three-chambered heart found?

The lines $x-y-2=0$,$x+y-4=0$ and $x+3y=6$ meet at a common point: