The angle of polarisation for a medium is $60^o$. What will be the critical angle for this medium?

Which branch of science is associated with the development and cultivation of forests?

All the springs in figures $(a)$,$(b)$,and $(c)$ are identical,each having a force constant $K$. The mass attached to each system is $m$. If $T_a, T_b$,and $T_c$ are the time periods of oscillations of the three systems respectively,then:

Which of the following taxonomic categories is being described by the given statements $(i-iii)$?
$(i)$ It is the basic unit of classification.
$(ii)$ It is defined as the group of individuals which resemble in their morphological and reproductive characters and interbreed among themselves and produce fertile offsprings.
$(iii)$ Human beings belong to the species sapiens which is grouped in the genus Homo.

The major product of the following reaction is

Three waves of equal frequency having amplitudes $10\,\mu m$,$4\,\mu m$,and $7\,\mu m$ arrive at a given point with a successive phase difference of $\pi / 2$. The amplitude of the resulting wave in $\mu m$ is: