What is common between vegetative reproduction and apomixis?

Fossil $X$ is older than fossil $Y$ if

Which of the following is a hydride?

Which of the following is not a polymer?

The property of hydrogen which distinguishes it from alkali metals is

$A$ body of mass $200\,g$ is tied to a spring of spring constant $12.5\,N/m$,while the other end of the spring is fixed at point $O$. If the body moves about $O$ in a circular path on a smooth horizontal surface with a constant angular speed of $5\,rad/s$,then the ratio of the extension in the spring to its natural length will be: