The species having tetrahedral shape is

If $A$ is the areal velocity of a planet of mass $M$,its angular momentum is

Which of the following oxides is the least acidic?

$A$ diverging lens with a focal length of magnitude $25 \, cm$ is placed at a distance of $15 \, cm$ from a converging lens with a focal length of magnitude $20 \, cm$. $A$ beam of parallel light falls on the diverging lens. The final image formed is:

The first biosphere reserve established in India for conserving the gene pool of flora and fauna and the lifestyle of tribals is

$A -$ Events after the formation of zygote are called post-fertilization events.
$R -$ In viviparous animals,a young one develops outside the mother's body.