The ratio between kinetic energy and the total energy of the electrons of a hydrogen atom according to Bohr's model is

$A$ charged particle with charge $q$ and mass $m$ starts with an initial kinetic energy $K$ at the centre of a uniformly charged spherical region of total charge $Q$ and radius $R$. Charges $q$ and $Q$ have opposite signs. The spherically charged region is not free to move and kinetic energy $K$ is just sufficient for the charged particle to reach the boundary of the spherical charge. How much time does it take the particle to reach the boundary of the region?

The enzyme enterokinase helps in the conversion of $............$.

$X$-rays are used in:

Which of the following is associated with the conservation of forests?

Which of the following are not characteristic features of $Fabaceae$?